German Chancellor Angela Merkel has distanced herself from Olaf Scholz, the Social Democratic Party's candidate to succeed her in the country's top job, in a bid to help revive the campaign of Armin Laschet, the flag bearer for her own party in an election this month.

Merkel dismissed Scholz's efforts to portray himself as her natural heir in the national election on Sept 26, when she will step down after 16 years in office.

Scholz, from the center-left SPD and a former mayor of Hamburg, has been serving as finance minister and vice-chancellor since 2018 under Merkel's coalition government. Merkel's Christian Democratic Union is the main party in the center-right coalition.

Scholz has outperformed his two major rivals, CDU candidate Laschet and Annalena Baerbock from The Greens, over the past months by selling himself as representing continuity from the Merkel era and by cashing in on rivals' missteps.

A snap poll after the first televised debate on Sunday showed that 36 percent of voters believed Scholz won, compared with 30 percent for Baerbock and 25 percent for Laschet.

Merkel on Tuesday said that there was a "huge difference" between Scholz and herself.

"With me as chancellor, there would never be a coalition in which The Left party is involved. As it is not clear whether this is the case with Olaf Scholz or not," she told a news conference in Berlin with Austrian counterpart Sebastian Kurz. "In this context, there is simply a huge difference for the future of Germany between me and him (Scholz)."

Scholz's refusal to rule out a coalition with The Left, known in Germany as Die Linke party, has raised some doubts over his campaign. Die Linke is regarded as the most left party represented in the Bundestag, the German federal parliament; it is a descendant of the Socialist Unity Party of Germany, the ruling party in the former East Germany.

Scholz did not rule out a coalition with The Left. He said such a move was "not good for democracy", and it was up to the voters to choose who should govern Germany, according to an interview with the Frankfurter Allgemeine Sonntagszeitung published over the weekend.

Deep concern

Merkel started campaigning for Laschet in early August. Her attack on Scholz has been viewed as reflecting the deep concern in the alliance of the CDU and the Christian Social Union in Bavaria over the recent lackluster performance by their candidate and as a strategy to win more German mainstream centrist voters to her side.

"Great amusement in Germany that SPD's #Scholz is adopting Merkel's '#Raute' or diamond hand sign. Must try it in a new business pitch," Andrew Marshall, vice-chairman of Cognito Media and a member of the Chatham House, said in a tweet on Tuesday, clearly referring to Scholz's strategy of mimicking Merkel.

Tom Nuttall, the Berlin bureau chief of The Economist, said there is an irony to Merkel's claims in relation to Scholz's refusal to rule out a coalition with The Left.

"The defining characteristic of her chancellorship has been an unwillingness to rule anything out until it is no longer feasible," he said in a tweet.