Armin Laschet has won the backing of German Chancellor Angela Merkel’s party to run as a centre-right candidate to succeed her in September’s elections.
Christian Democrat (CDU) leader Mr Laschet was supported by 77.5% of the party’s executive board members.
His rival Markus Söder, who heads the CDU’s Bavarian sister party the CSU, was supported by 22.5% of the board.
Mr Söder had earlier said it was up to the CDU to choose who would represent the conservative alliance.
Mrs Merkel, leader since 2005, is set to stand down at the 26 September federal elections.
Mr Laschet, 60, was elected CDU leader in January, and is also premier of North Rhine-Westphalia – Germany’s most populous state.
Mr Söder, 54, is premier of Bavaria.
More commonly a leader of the CDU, the larger party, would be expected to become the two parties’ candidate. But at present, polls suggest Mr Söder would be the more electable choice.
A candidate from the CSU has never won a federal election before. Two previous attempts by CSU leaders failed in 1980 and 2002.
Mrs Merkel has not publicly expressed a preference for either potential candidate.
The conservative alliance is facing a decline in popularity , slipping to about 27% in polls.
The Social Democrats have already announced their candidate for chancellor, Finance Minister Olaf Scholz.
And on Monday the Green party announced a candidate, Annalena Baerbock, for the first time in its history.
Ms Baerbock, 40, is likely to be the only woman in the race.