BERLIN (AP) ― Chancellor Angela Merkel’s coalition suffered a new setback and Germany’s main opposition parties celebrated gains in a state election Sunday that came as Merkel’s unpopular government grapples with the eurozone debt crisis and other challenges.

The vote in Mecklenburg-Western Pomerania, a northeastern region where Merkel’s parliamentary constituency is located, was the sixth of seven German state elections this year. Most of those have gone poorly for the chancellor’s center-right coalition.

The center-left Social Democrats, who lead the state government but are in opposition nationally, won 35.7 percent of Sunday’s vote ― about five points more than five years ago, provisional official results showed.

The other winners were the opposition Greens, who have been riding high in national polls.

They won 8.4 percent, entering the state legislature for the first time ― which means they are now represented in all 16 German regional parliaments. National leader Cem Ozdemir called that “a true sensation.”

Merkel’s conservative Christian Democratic Union, however, slid to 23.1 percent from nearly 29 percent in 2006, its worst showing yet in the state.

And its partner in the national government, the Free Democratic Party, slumped to just 2.7 percent ― losing more than two-thirds of its support and its seats in the state legislature.

“The CDU is, of course, disappointed by this election result,” senior federal lawmaker Peter Altmaier told ARD television.

He added that it pointed to the need “to stand together. ... This is the precondition for people to have confidence in our policies.”

Over the coming weeks, Merkel faces the task of swinging skeptical center-right lawmakers in Berlin behind the latest measures aimed at keeping debt-troubled eurozone countries afloat.

That adds to issues such as this year’s abrupt decision to speed up Germany’s exit from nuclear power, the country’s abstention in a U.N. vote on the no-fly zone over Libya, and constant internal feuding over plans for tax cuts ― all blamed for undermining center-right support.

The pro-business FDP has taken much of the blame for the squabbling and has struggled to reverse a slump in polls since Philipp Roesler, the new vice chancellor, took over as leader in May.

“This is a defeat that tastes bitter,” said its general secretary, Christian Lindner. “For us in Berlin, this means (we need) to work with discipline on the bread-and-butter issues ― the euro, the economic situation, jobs.”

The far-right National Democratic Party won 6 percent of the vote ― enough to retain seats in the state legislature in Schwerin, although it lost some support.

Mecklenburg-Western Pomerania is one of two regions where the party, which has no seats in the federal parliament, has local lawmakers. Low turnout of 51.4 percent probably helped it.

Voting in one constituency was delayed until Sept. 18 following a candidate’s death. But that isn’t expected to change the outcome significantly.

About 1.4 million people were eligible to vote in the sparsely populated state on the Baltic Sea coast ― an economically struggling region once part of communist East Germany.

It is currently run by a left-right “grand coalition” of the Social Democrats, who provide popular Gov. Erwin Sellering, and Merkel’s CDU.

Sellering could continue that alliance or form a coalition with the ex-communist Left Party, whose support was up slightly at 18.4 percent ― though that appears less likely. That combination ran Mecklenburg-Western Pomerania until 2006.

This year’s last scheduled state election comes on Sept. 18, when opposition-run Berlin votes.