The SPD, facing record low support levels, will elect a new leader during a party conference in December and review the coalition with Merkel's conservatives. Scholz is the highest profile candidate in the party leadership race.

Scholz belongs to a camp in his party that is in favour of remaining in Merkel's coalition, which the SPD joined reluctantly after suffering painful losses in the 2017 national election. Leftist SPD members are fed up with their party propping up Merkel and prefer to rebuild in opposition.

"A review will be made. And in December the party will make a decision on how we go forward and we will all have to abide by the decision, and this includes myself," Scholz said during a talk show on German public broadcaster ZDF.

Pressed by the moderator on whether he would give up his post as finance minister if SPD delegates decide it was time to leave Merkel's coalition, Scholz said: "The SPD will decide which way we go and the decision must be valid for all."

The SPD has been without a leader since Andrea Nahles resigned in June after her party suffered its worst losses in the elections to the European Parliament.

Scholz became defensive when a journalist taking part in the talk show suggested that SPD lawmakers could decide not to give party members a chance to review the coalition to avoid a vote in favour of quitting Merkel's government.

An opinion polls published by ZDF showed that 52% of SPD members believe their party would be better served if it remained in the coalition until the end of its mandate in 2021.

About 45% said the party should quit the government, which would either trigger a snap election or lead to a minority government.

Polls show Merkel's conservatives would come first in a new election, with the Greens a close second, and the SPD in third place, just ahead of the far-right Alternative for Germany (AfD).

The SPD's leadership race started on Wednesday with 17 candidates facing hustings. The protracted race will see candidates attending 23 regional conferences in the next six weeks.

The result of the conferences is due on Oct. 26 and if no candidate wins more than half the vote there will be a runoff.