By Isabelle Le Page

and Michelle Fitzpatrick

BARELY a year after promising to jolt Germany's oldest party back to life, Martin Schulz has said he will step down as leader of the Social Democrats — weakened by a poll debacle and a U-turn too many.

Hours after clinching a hard-fought coalition pact with Chancellor Angela Merkel's conservatives on Wednesday, Schulz declared he was not the right person to lead the "process of renewal" his beleaguered party needed.

"I have tried to give the party strength and courage, but I can't do justice to the expectations," he said, tapping the SPD's parliamentary group leader Andrea Nahles as his replacement.

The former European Parliament chief said he now wants to serve as foreign minister in Merkel's next government, one of three crucial portfolios he managed to snatch for the SPD in the grueling coalition talks.

But the renewed tie-up with Merkel's conservatives is far from guaranteed, as Schulz has promised to give the SPD's 460,000 members the final say on whether to approve the coalition deal.

The referendum could be tight as many grassroots SPD voters are still fuming that Schulz backtracked on his pledge to go into opposition after leading the party to a historic low of 20.5 percent in September's election.

"Schulz has made many promises he couldn't keep in recent months," the Sueddeutsche Zeitung daily wrote, adding that he had "lost credibility".

By setting his sights on the glamorous foreign ministry role, the 62-year-old appeared to be eyeing an elegant exit "from an increasingly precarious situation", it added.

Down but not out

Some observers say Schulz's woes are not all his own doing.

September's tricky election saw mainstream parties hamorrhage votes while the far-right AfD made huge inroads, leaving Merkel without an obvious coalition partner.

After her attempt to forge an untried alliance with two smaller parties broke down in November, she pinned her hopes for a stable government on the SPD.

Faced with the alternative of snap polls that could further boost the AfD, Schulz caved in to pressure to reconsider for the good of the nation — despite initially categorically ruling out another term alongside Merkel.

But it's his sudden eagerness to take up a ministerial post that has most flummoxed supporters, contradicting his earlier insistence he would "not enter into a Merkel cabinet".

"The first U-turn can be forgiven," the regional Augsburger Allgemeine newspaper wrote.

"But if Schulz becomes minister, he would be breaking a personal promise."

After riding high in the opinion polls when he first took the helm of the SPD last year and inspired a wave of new party memberships, support for Schulz has slumped to an all-time low.

The latest surveys suggest just 14 percent of Germans would want him as chancellor, while the SPD would score a record-low 17 percent if elections were hold now.

Schulz's downward trajectory prompted the Forsa polling institute to dub him "the loser of the year" in 2017.

But commentators warn against writing Schulz off too soon. — AFP