Social Democratic Party (SPD) Chairman Sigmar Gabriel | EPA/Daniel Karmann Sigmar Gabriel, the ‘kamikaze’ candidate Merkel’s coalition partner and potential challenger in 2017 is finding it hard to keep his center-left party happy.

BERLIN — The German language doesn't distinguish between 'politics' and 'policy' but Sigmar Gabriel is learning the difference the hard way, as the Social Democratic Party (SPD) leader copes with probably the worst crisis of his career.

The pugnacious 56-year-old party leader, who is deputy chancellor in Angela Merkel's conservative-led 'grand coalition,' also runs the economy ministry, which in Germany includes the trade and energy portfolios. In his struggle to reconcile the wishes of his crisis-ridden party with his policy decisions, Gabriel has alienated lots of people in the party.

“He managed to drive even those that were always on his side to despair,” said one party official in the Bundestag (lower house of parliament), speaking on condition of anonymity.

In the run-up to 2017's federal elections, when he is supposed to challenge conservative leader Merkel for the chancellorship, Gabriel faces two crucial state elections in September and a key party congress that could seal his fate and that of his party, which has fallen into what looks like terminal decline since winning the 1998 elections with more than 40 percent of the vote.

By May this year, support for the Social Democrats — Germany's oldest political party, founded as a workers' movement in the late 19th century — had fallen below 20 percent for the first time in the post-war period. It has clawed back a few points since then, but many genossen (comrades) have lost faith in their stumbling party chief, seeing his three years as economy minister as a series of policy flip-fops and PR debacles.

Gabriel continues to drive people up the wall, again and again, particularly within the left wing of the party — Party official

“Thanks to the high frequency with which he changes his mind, he has become untrustworthy,” said another senior SPD lawmaker. “People don’t believe him anymore.” Furthermore, Gabriel's crisis management skills are "catastrophic," his critics say.

Things have gotten so bad that SPD officials privately describe presenting Gabriel as their candidate against Merkel next year as a Kamikaze-Aktion. In an opinion poll published this week, 46 percent of respondents from across the political spectrum said they would like to see Merkel continue as German chancellor; Gabriel scored just 15 percent.

Late last month, the Social Democrat state premier of Schleswig-Holstein, Torsten Albig, told a regional broadcaster that in the face of such popularity for Merkel, the SPD might be best advised not forwarding any candidate for chancellor next year — not exactly a ringing endorsement of the party chief.

Up the workers

Gabriel's defenders include deputy party chief Ralf Stegner from the left wing of the SPD, who told POLITICO: “Sigmar Gabriel is not isolated within the party, quite the opposite. And I would say that during the last couple of months he has made up lost ground — by stressing publicly, again and again, that our core competence is and remains the issue of social justice.”

The latest bruising episode for the economy minister involved his decision earlier this year to allow supermarket giant Edeka to take over 450 branches from a competitor in defiance of the antitrust office, which had recommended the deal be blocked.

When a court ruled against the minister's decision in July, Gabriel's response to media reports of backroom negotiations with lobbyists was that he had been trying to protect jobs. “This is about sale-ladies, about packers, about fork-lift operators,” he told journalists during a political rally in Rostock earlier this week.

It wasn't the first time Gabriel had cause to question his eagerness to snag the economy portfolio when the SPD entered the coalition with Merkel's conservatives in 2013. From the Social Democrats' point of view, the powerful ministry was seen as an opportunity to strengthen the party's profile following its second-worst election outcome of the post-war period. Their 25.7 percent share of the vote was blamed on the SPD's perceived weakness on economic policy issues.

The EU-U.S. free-trade agreement — TTIP — has become a similar lose-lose situation for Gabriel.

Running the economy ministry seemed like a good idea at the time, not least because implementing the Energiewende — Merkel's decision to ditch nuclear power and accelerate the transition to renewable energy — would give Gabriel ample opportunity to distinguish himself as a strategic statesman, capable of replacing Merkel at the next elections.

Things turned out differently, however: Gabriel failed to shield consumers from subsequent rises in electricity costs, which continue to burden the economy: next year alone, the "renewables reallocation charges" which are supposed to mitigate the costs of the energy transition will rise by another 10 percentage points, according to industry think-tank Agora Energiewende.

Economy ministry spokeswoman Beate Braams said Gabriel "never spoke about bringing down energy prices. He clearly formulated his goal as stabilizing the cost of energy.”

She did not respond to a question from POLITICO about the minister facing the worst crisis of his career, and Gabriel himself declined to be interviewed for this article.

Potential challenger

For a party that still sees itself as the champion of the ordinary German, it was damaging to fail to deliver on the SPD promise not to allow the Energiewende to happen at the cost of domestic consumers. At the same time, the party's traditional trade union supporters and some regional governments run by the SPD were furious about the phasing out of brown coal plants.

The EU-U.S. free-trade agreement — TTIP — has become a similar lose-lose situation for Gabriel, who started his term as minister promoting it as a boost for the economy but had performed a U-turn by spring this year. When Merkel said the aim was to finish negotiations on TTIP in 2016, Gabriel — who had come under pressure within the party, whose energy spokesperson in the Bundestag last month declared TTIP "de facto dead" — criticized her stance and warned against rushing into an agreement.

Now representatives of Germany's business lobby express disappointment with his lack of support for the trade deal while the left wing of the SPD still considers him too accommodating in his approach to TTIP.

“Gabriel continues to drive people up the wall, again and again, particularly within the left wing of the party,” said a party official — the kind of criticism echoed in newspaper editorials that have started to irritate the famously thick-skinned SPD leader.

While Merkel's Christian Democrats largely refrain from attacking Gabriel because they see him as an easy rival to beat in 2017, and many potential internal rivals in the SPD are holding back because the toxic nature of his position is so apparent, there is now at least one potential candidate in the party to replace him: Olaf Scholz, the 58-year-old head of the city-state of Hamburg and one of the most popular regional premiers in the country.

In comments last weekend seen as a tacit declaration of interest, Scholz told the Bild am Sonntag newspaper: "The SPD has a chance of winning the chancellery. The gap between the conservatives and the SPD has become smaller.”

“If the citizens of Germany could see a Social Democrat as chancellor, we would quickly win another 10 percent points.”

Next month, two of Germany's 16 federal states — Mecklenburg-Vorpommern and Berlin — hold elections, and the Social Democrats are expected to suffer a crushing defeat in at least one of those contests.

Around the same time, 250 SPD delegates will vote on how to deal with the EU-Canada free trade agreement, known as CETA, which is widely seen as a precursor to the bigger transatlantic trade deal with the U.S.

A vote against the trade deal would deliver a potentially fatal blow to Gabriel's ambitions, especially if it comes on the heels of a regional election setback.

"The state elections and the convention will decide Gabriel's political survival," said one SPD source.