By Madeline Chambers
BERLIN (Reuters) - After a string of gaffes from their leader in the last few months, Germany's Social Democrats (SPD) are openly doubting whether Sigmar Gabriel can beat conservative rival Angela Merkel in the next election due in 2017.
One SPD state premier has even quipped that it may not be worth putting up a candidate against the incumbent chancellor, who is near the peak of her powers after 10 years in office.
With the SPD trailing the conservatives by almost 20 points in most opinion polls, a Forsa survey this week showed that only 14 percent of voters would choose Gabriel were there to be a direct vote for chancellor.
That compares with 56 percent for Merkel, who is widely expected to seek a fourth term in the 2017 parliamentary election although she has yet to confirm her candidacy.
Gabriel, 55, has a difficult job. As deputy chancellor in Merkel's grand coalition, he has to show he is fit to lead the nation while also heading a centre-left party whose policies are at odds with much of German public opinion, especially on whether to pour yet more money into Greece.
A former school teacher, Gabriel was a protege of the last Social Democrat chancellor Gerhard Schroeder but lacks his acute political instincts. While Gabriel remains likely to lead the SPD in 2017, doubts persist even within his own party: only 35 percent of SPD members think he is a suitable candidate for chancellor.
Gabriel had a strong first year sharing power in Merkel's right-left coalition, pushing through SPD policies such as a minimum wage. But now he is sliding from one mishap to another, lampooned by media as "Mr Zig Zag" for his policy reversals.
"Can he be chancellor?" asked the top-selling Bild newspaper, which often supports Merkel. In an article on Thursday, Bild listed his slip-ups from a visit earlier this year to a march held by the anti-Islam PEGIDA group to flip-flops on data protection laws, energy policy and an EU-U.S. trade deal.
A Jekyll and Hyde approach to Greece has also hurt. Gabriel has switched from espousing an end to austerity policies demanded by the country's creditors to accusing Greeks of tearing down bridges to Europe. He even appeared to go along with a proposal from hardline finance minister Wolfgang Schaeuble that Greece should temporarily leave the euro.
To top it all, a visit Gabriel made last week to Tehran to drum up business was widely criticised at home for being overhasty, coming only a few days after Iran struck a nuclear deal with world powers.
His description of Iranians as "friends" angered Jewish communities - a blunder in Germany due to the legacy of the Holocaust and especially for the SPD, whose opposition to Hitler's Nazis remains a source of pride.
Despite being the SPD's longest-serving leader since the legendary Willy Brandt, he has lost support among rank and file.
"I've been in the SPD for 20 years ... But unfortunately I can't support you," voter Bjoern Uhde wrote on a supporters' website earlier this month. "Mr Zig Zag: with your path that is destroying the SPD ... you will never become chancellor."
Schleswig-Holstein's SPD state premier Torsten Albig summed up the frustration last week when he praised Merkel for doing an excellent job and suggested the SPD may have to ditch aspirations to be the ruling party in 2017. "Whether naming a candidate for chancellor is still right or not, remains to be seen," he said.
NO COMPETITION
Gabriel, who is also economy minister, has defended his Iran trip, saying it was necessary to normalise relations.
Asked this month about disquiet in his party, he said debate was healthy. "A silent party is a stupid party," he snapped, adding it was too soon to decide on running against Merkel.
Gabriel, who jokes about being overweight, has won sympathy for talking about estrangement from his Nazi father and for taking off time to collect his young daughter from nursery.
Given the lack of clear party rivals, most pundits are still betting on Gabriel, a passionate speaker who brought a divided party together after the coalition deal in 2013.
"Gabriel has no competition," said Gero Neugebauer, analyst at Berlin's Free University. But he must realise that being the government's "policy engine" in government will not win votes.
"He is mistaken if he thinks people want to look at a car's engine. They look at the driver - that's Mrs Merkel," he said.
SPD hopes of a coalition with the Greens and radical Left party in 2017 are also effectively dead as the Left party is rallying behind a more militant leadership.
Also bad news for the SPD are a revival in the pro-business Free Democrats, who could offer the conservatives another coalition option, and the breakup of the eurosceptic Alternative for Germany, which removes a threat to Merkel's party.
Some SPD members fear a repeat of the 2009 election when the party's vote slumped to a post-war low of 23 percent. That followed a previous spell in a grand coalition, when Merkel took the credit for presiding over a robust economy despite the global financial crisis. This time around, Merkel is likely to mop up votes for steering Germany through the euro zone debt crisis.
Analysts say Gabriel is in an unenviable position. "He has to show he is capable of government yet has opposing views to the conservatives," said Thomas Jaeger, analyst at Cologne University. "And steer a course between an electorate that says: 'no money to Greece, no more refugees', and a party with totally different views."
(editing by David Stamp)