Germany’s Green party walked out on exploratory coalition talks with Chancellor Angela Merkel’s Christian Democrats on Tuesday, leaving her with little alternative to forming a “grand coalition” with the Social Democrats.

Merkel won 41.5 percent of the votes in an election last month that left her party just five seats short of a majority in the lower chamber of parliament. The Greens lost support and finished fourth after Die Linke. Both the Christian and Social Democrats have ruled out forming a government with the latter which is the successor to former East Germany’s ruling communist party.

Although a pact could have benefited both parties electorally — socially liberal voters sympathize with the Greens’ cosmopolitanism but are doubtful they are ready for national government while the conservatives could have expanded their appeal to young and women voters — there was simply not enough common ground to enter a coalition, officials said. Climate targets, energy policy and taxation were among the main sticking points.

That leaves the Social Democrats in a stronger position. They have already signaled they could accept no higher taxes on the rich, which they campaigned on, but are unlikely to shelve their demand for a national minimum wage — which Merkel fears will harm German competitiveness.

Even such a signature achievement might not prevent them from suffering the same fate in the next election as they did in 2009, however, when they lost more than 10 percent support after supporting Merkel in the last “grand coalition.” A vast majority of Germans favors another left-right government but many voters also say they see little difference between the two major parties anymore.

Social democrat party members will have their say on a coalition deal which puts further pressure on leaders to extract concessions from the right.

Merkel’s supporters are no less enthusiastic. Her Bavarian sister party, which is more conservative, has rejected tax hikes altogether while a deal could convince rightwingers to vote for Alternative für Deutschland in next year’s European Parliament elections. The Euroskeptics failed to cross the 5 percent election threshold last month but enjoy considerable support among voters who are tired of bailing out weaker states in the periphery of the eurozone.