Berlin - Foreign Minister Frank-Walter Steinmeier has deposed Chancellor Angela Merkel from top of the list of Germany's most popular politicians, according to a survey released Friday.

An opinion poll conducted for German semi-public broadcaster ZDF showed the Social Democrat (SPD) minister with a rating of 1.7, marginally higher than Merkel's 1.6.

Steinmeier is considered a potential challenger to Merkel for the chancellorship in national elections due to take place in September 2009.

He is currently vice chancellor in the grand coalition with Merkel's Christian Democratic Party (CDU).

The survey showed that 39 per cent would vote for the CDU against 28 per cent for the SPD if elections were to be held now.

The opposition Left party would poll 11 per cent followed by the environmentalist Greens and business-oriented Free Democrats, both on 9 per cent.

SPD leader Kurt Beck saw his popularity decline to minus 0.5, with only 19 per cent favouring him as the man to take on Merkel in next year's election.

The poll of more than 1,200 eligible voters was conducted by the Election Research Group from April 1 to 3. There was a margin of error of between 1.4 and 2.7 per cent.