In a statement posted on Friday to X, formerly known as Twitter, Freeland expressed her intention to run and said she would hold a formal campaign launch in the coming days.

“I’m running to fight for Canada,” she wrote.

Freeland recently fell out with Prime Minister Justin Trudeau over the direction of the country’s financial policies. Her resignation from her post in December was a blow to Trudeau’s already-shaky hold on the Canadian government, helping to usher in his own resignation after nine years as prime minister.

• Who might replace Trudeau as Liberal Party leader?
• Canada’s finance minister quits over Trump tariff dispute with Trudeau

Freeland had long been one of Trudeau’s closest allies in his Liberal Party. She held the key role of Canada’s finance minister starting in 2020 – the first woman to hold the position – and helped to lead the country through the pandemic and its aftermath.

The two disagreed on how to address US President-elect Donald Trump’s threat of tariffs, among other financial policies as Canada faced a C$60b deficit ($42bn; £33bn).

Following his win in November, Trump, who takes office on Monday, suggested that he would impose potential 25% tariffs on Canadian goods.

In a public resignation letter, Freeland criticised Trudeau’s leadership, denounced his use of “costly political gimmicks” and said Canada must push “back against ‘America First’ economic nationalism”.

Freeland further addressed Trump’s tariff threats in a piece she penned on Friday for the Toronto Star newspaper, arguing that Canada “must take President Trump at his word.”

“Florida orange growers, Michigan dishwasher manufacturers and Wisconsin dairy farmers: brace yourselves,” she wrote, arguing that Canada should retaliate hurts if Trump imposes his promised 25% tariffs.

With Trudeau stepping down, his party must now find a new leader to compete in a general election. Liberals will vote for their new leader on 9 March.

Former Bank of Canada and Bank of England governor Mark Carney announced his run on Thursday. Freeland had been expected to run against him in seeking the party’s top position.

The two already have received endorsements from a handful of Liberal MPs.

Born to a Ukrainian mother in the western province of Alberta, the 56-year-old, who attended Oxford as a Rhodes Scholar, was a journalist before entering politics.

She entered the House of Commons in 2013, representing a central Toronto riding, and two years later joined Trudeau’s cabinet with a trade brief after he swept the party to power.

Freeland has been credited with helping renegotiate the free trade agreement with Canada, the US and Mexico during Trump’s first term in office, in talks that were often described as tense.

After her resignation in December, Trump referred to her as “toxic” in a post on Truth Social, and remarked that “she will not be missed.”

If Freeland wins the Liberal Party leadership, she would face-off with Conservative leader Pierre Poilievre, whose party is leading in national polls, in the next general election.

On Friday morning, Poilievre released a video highlighting her partnership with Trudeau over the years under his government. “She’s just like Justin,” the Conservative leader said.

The next Canadian general election must be held on or before October of this year, and could come as early as this spring.

The pledge follows a threat from President-elect Donald Trump to impose, when he takes office in January, a 25% tariff on Canadian goods if the country does not secure its shared border to the flow of irregular migrants and illegal drugs.

Economists say such tariffs could strike a blow to Canada’s economy.Announcing details of the plan, Canada’s minister of finance and intergovernmental affairs said the federal government would devote C$1.3bn ($900m; £700bn) to the plan.

The measures “will secure our border against the flow of illegal drugs and irregular migration while ensuring the free flow of people and goods that are at the core of North America’s prosperity”, Minister Dominic LeBlanc said on Tuesday.

The five pillars of the plan cover the disruption of the fentanyl trade, new tools for law enforcement, enhanced coordination with US law enforcement, increased information sharing and limiting traffic at the border.

They include a proposed aerial surveillance task force, including helicopters, drones and mobile surveillance towers between ports of entry.

The government is also giving the Canada Border Service Agency funds to train new dog teams to find illegal drugs, and new detection tools for high-risk ports of entry.

And LeBlanc provided further detail on the so-called “joint strike force” for Canadian and US authorities, saying it would include “support in operational surges, dedicated synthetic drug units, expanded combined forces, special enforcement units, binational integrated enforcement teams, and new operational capacity and infrastructure”.

The new plan appears to correspond to the concerns publicly disclosed by Trump in recent weeks: the flow of fentanyl and undocumented immigrants into the US.

The number of crossings at the US-Canada border is significantly lower than at the southern border, according to US Border Patrol data on migrant encounters, as is the amount of fentanyl seized.Mexico is also facing a 25% tariff threat.

LeBlanc said he and other officials had a “preliminary” conversation with Trump’s incoming “border tsar” Tom Homan about the new plan.

“I’m in encouraged by that conversation,” he said.

LeBlanc was present at a meeting last month between Prime Minister Justin Trudeau and Trump at Mar-a-Lago, a trip reportedly meant to head-off the levy.

The announcement comes on LeBlanc’s first day as Canada’s finance minister.

The longtime ally to Trudeau was hastily sworn in on Monday after the surprise resignation of Chrystia Freeland, who served as both finance minister and deputy prime minister.

Freeland quit her posts with a scathing open letter to Trudeau in which she outlined disagreements she had with him on spending and “the best path forward for Canada”.

Her abrupt exit from cabinet has put additional strain on Trudeau’s weakened minority government.

On Tuesday, in a speech to party faithful at a Liberal holiday event, a defiant Trudeau said there are “always tough days and big challenges” in politics.

“But this team doesn’t hold the record for the longest minority in Canadian history because we shy away from these moments, we put in the work, whether it’s easy or hard.”

By the end of a frenetic Monday, a new finance minister was in place, but Trudeau was facing calls from members of his own Liberal Party to quit.

Without directly referring to the news, the prime minister told party donors at an event in Ottawa: “It’s obviously been an eventful day. It has not been an easy day.”

In her scathing resignation letter – published on the day she was due to deliver an economic statement – Freeland cited disagreements with her long-time ally on how to respond to the threat of tariffs from Donald Trump.

The US president-elect, who will return to the White House in January, has vowed to impose a levy of 25% on imported Canadian goods unless the shared border is made more secure.

Economists say the tariffs could have a devastating effect on Canada’s economy.In her letter, Freeland accused Trudeau of choosing “costly political gimmicks” over addressing the threat posed by Trump’s “aggressive economic nationalism”.

Trump himself later responded to Freeland, posting that her “behaviour was totally toxic, and not at all conducive to making deals which are good for the very unhappy citizens of Canada”.

Freeland said her decision came after Trudeau told her last week that he no longer wanted her to be the government’s top economic adviser.

Her departure blindsided the government, leaving the fate of the scheduled economic update in the air for hours and bringing Trudeau and his shaky minority Liberals to the brink.

In a further blow, the Liberals lost control of the Cloverdale-Langley City seat in British Columbia, after a by-election win for rival Conservatives. It was the Liberals’ third by-election defeat of the year.

Freeland’s sudden exit as finance minister earlier in the day “just makes Canada look quite confused and uncertain”, Chris Sands, director of the Wilson Center’s Canada Institute said.

“Trudeau finds himself a little bit alone, not super close to any of his ministers, with the big, talented ones mostly now having left,” he added.

Mr Sands said Trump’s win in November’s US presidential election has caused a split among US allies, including Canada.

“Do you respond to Trump by pushing back and standing firm, or do you respond by trying to find a way to avoid conflict?” he said.

Trudeau has made overtures to Trump, including flying to Mar-a-Lago, the president-elect’s Florida estate, last month to dine with the president-elect.

But Freeland’s perspective, said Mr Sands, was closer to that of Mexico – also facing a tariff threat – and Mexican President Claudia Sheinbaum.

Mexico has positioned itself under the idea that “now is the time to say no, to push back, to take a fighting stance”, he said.

Many politicians remember the challenges they faced during Trump’s first term in office, he added.

“He hasn’t been inaugurated yet, but people are already reacting as though he was the president and taking serious measures.”

Freeland, who also served as deputy prime minister, had been Ottawa’s lead during the first Trump administration in the successful re-negotiation of the US-Canada-Mexico free trade pact.

It was “a really stressful and overwhelming process for Canada”, Mr Sands said.

In addition to the members of the prime minister’s own party who called on him to quit, Canada’s three opposition party leaders said on Monday that Trudeau must go.

Pierre Poilievre, leader of the opposition Conservative Party of Canada, called for a federal election as soon as possible.

“Everything is spiralling out of control. We simply cannot go on like this,” he said.

Canada’s next federal election must be held in October, at the latest.

Laura Stephenson, chair of the political science department at Western University, told the BBC that it was not clear that a change in leadership would affect the current US-Canada dynamic.

“I have no confidence that Trump will react any differently to Poilievre than he does to Trudeau,” she said.

After nine years in power, Trudeau has faced growing calls to resign over concerns he is a drag on his party’s fortunes.

The Liberal leader’s approval rate has plummeted from 63% when he was first elected to 28% in June of this year, according to one poll tracker.

Opinion polls also suggest the Liberals could face a devastating loss to the Conservatives if an election was held today.

Some Liberal members of parliament have been pressuring Trudeau for months to step down – eight MPs publicly expressed this sentiment on Monday, Canadian newspaper The Globe and Mail reported.

In a meeting with his caucus following Freeland’s resignation on Monday, Trudeau reportedly heard some of those calls for him to quit directly. Others also expressed their concerns and reservations about his leadership.

Trudeau addressed them by saying he is not immediately stepping down, but that he will reflect on the day’s events, according to sources who spoke to Canadian media about the meeting.

Trudeau did not take questions on his way to the fundraiser in Ottawa, but he told the crowd he was “damn proud” of his government’s accomplishments.

In brief remarks, he said working for Canadian values was “at the core of what makes us Liberals”.

“That’s why we show up here, even on the toughest days as a party.”

Trudeau has defied previous calls to step aside and has said repeatedly that he plans to run in the next federal election.

Also on Monday, the leaders of Canada’s provinces and territories met in Toronto to address Trump’s tariff threat.

“It’s chaos right now up in Ottawa”, said Ontario Premier Doug Ford.

Ford said the premiers will “make sure that we tell the world there is stability here, there is certainty here in Canada”.

She announced her resignation in a letter to Trudeau on Monday, in which she said the two have been “at odds about the best path forward for Canada”, and pointed to the “grave challenge” posed by Trump’s policy of “aggressive economic nationalism”.

Freeland said the decision comes after Trudeau informed her last week that he no longer wanted her to be his government’s top economic adviser.

Her resignation came hours before she was due to provide an annual fiscal government update in parliament.

In recent days, the two have also reportedly been in a dispute over a policy that would have delivered a C$250 ($175; £139) cheque to every eligible Canadian.

In her publicly-shared resignation letter, Freeland said Canada needs to keep its “fiscal powder dry” to deal with the threat of sweeping tariffs from US President-elect Donald Trump.

She added this means “eschewing costly political gimmicks” that Canada cannot afford.

Trump has promised to impose a levy of 25% on imported Canadian goods, which economists have warned would significantly hurt Canada’s economy.

Referencing the tariffs, Freeland called them a “threat” that needs to be taken “extremely seriously”.

She added that this means “pushing back against ‘America First’ economic nationalism” and working with unity in response to these tariff threats.

Freeland and Trudeau were reportedly in disagreement over a series of recently-proposed policies by the prime minister designed to address the country’s cost-of-living crisis.

Among them is a cheque of C$250 that the government wanted to send to every Canadian earning less than C$150,000 annually. These cheques were expected to cost the federal government a total of C$4.68bn.

Another is a temporary tax break on essential items during the holidays which is anticipated to cost C$1.6bn in lost tax revenue.

Freeland’s office had reportedly been concerned about the price of these two policies, saying they are economically unwise at a time when the country’s deficit is growing.

The tax holiday has since been approved in the House of Commons, but the C$250-cheques hit a hurdle when the New Democratic Party – a centre-left party in parliament – signalled it would not lend its support to the policy unless it is expanded.

A poll by the Angus Reid Institute showed that four out of five Canadians viewed the cheques as a political move designed to win public goodwill as Trudeau’s popularity plummets.

Freeland, who also holds the position of deputy prime minister, has long been one of Trudeau’s closest allies within his Liberal party. She has held the key role of Canada’s finance minister since 2020, helping to lead the country through the pandemic and its aftermath.

She replaced former Finance Minister Bill Morneau, who also resigned from his post amid a dispute with Trudeau over government spending policies, as well as conflict-of-interest allegations he faced involving a youth charity.

Other members of the Liberal party’s cabinet have since reacted to her resignation.

“These are difficult and deeply personal decisions and obviously she’s made that decision and I respect her for it,” said Patty Hajdu, Canada’s minister for indigenous relations.

Minister of Transport Anita Anand described Freeland as a “good friend,” and added: “This news has hit me really hard and I’ll reserve further comment until I have time to process it.”

It is unclear if the fall economic statement will be delivered on Monday as planned in light of Freeland’s resignation. A government official told Reuters news agency that the finance ministry is determining next steps.

Canada’s public broadcaster CBC reported that Freeland’s resignation was not expected today, citing a senior federal government source.

Freeland said she intends to stay on as a Liberal member of parliament, and that she will run again in Canada’s upcoming election, which must be held on or before October.

Her resignation comes after another cabinet member, housing minister Sean Fraser, announced he will not be seeking re-election, saying he wants to spend more time with his family.