(Bloomberg) -- Angela Merkel endorsed Armin Laschet, her bloc’s candidate to succeed her as chancellor, while taking a shot at his Social Democratic rival in an unusually direct intervention in the election campaign.

A government led by her conservative alliance with Laschet as chancellor would be the “best path for our country,” Merkel said in a feisty speech in the Bundestag on Tuesday.

“His government would stand for stability, reliability and restraint,” she said in her final official appearance in parliament before the Sept. 26 vote. “It matters who runs the country.”

She criticized the fact that the SPD’s Olaf Scholz, the current front-runner, hasn’t ruled out a coalition with the anti-capitalist Left party, and also attacked a recent comment from her vice chancellor, who appeared to suggest that Covid-19 vaccinations are still experimental.

“No one getting vaccinated was a guinea pig,” she said, alluding to a comment he made in a recent interview. “Neither me nor Olaf Scholz.”

Less than three weeks before the election, the German leader led the debate that will also include the three main candidates seeking to replace her -- Scholz, Laschet and the Green party’s Annalena Baerbock.

Scholz, a distant third over most of the summer, has turned the contest around, vaulting into the front-runner role with the SPD topping the polls. Laschet has failed to reach voters and mounted a gaffe-prone campaign, while Baerbock has been on the defensive over accusations of plagiarism.

Merkel has sought to staunch the fallout, wading into the campaign on Sunday with a more full-throated endorsement of Laschet, even as polls show Scholz’s momentum holding steady.

©2021 Bloomberg L.P.