Updated

A prominent member of Germany's main center-left party is questioning whether it has any chance of unseating Chancellor Angela Merkel in the country's next election, and even whether it needs a candidate for the top job.

The Social Democrats are currently the junior partners in a "grand coalition" of Germany's biggest parties led by Merkel's conservative Union bloc.

They've pushed through popular policies such as a national minimum wage. However, opinion polls have barely moved since 2013 elections: they show the Social Democrats trailing the conservatives by 15 points or more.

Schleswig-Holstein state governor Torsten Albig said in an interview with NDR television broadcast Thursday that simply participating in a government could be a legitimate election aim.

He says "it is difficult to win an election against this chancellor."