Updated

The central German region of Hesse was voting Sunday in a state election marked by discontent with infighting in the national government and expected to help determine whether Chancellor Angela Merkel's administration has a long-term future.

The election for the state legislature in Hesse, which includes Germany's financial center, Frankfurt, comes with support for the country's governing parties sliding and tensions high in a federal coalition in office only since March.

Merkel's conservative Christian Democratic Union is defending its 19-year hold on Hesse, previously a stronghold of the center-left Social Democrats, the chancellor's coalition partners in Berlin. A disastrous result for either or both parties could further destabilize the national government and ultimately the position of Merkel, Germany's leader of the past 13 years.

Two weeks ago, two of the federal governing parties — the Christian Social Union, the Bavaria-only sister to Merkel's CDU, and the Social Democrats — were battered in a state election in neighboring Bavaria.

That has given extra significance to the election in Hessen, which is home to 6.2 million of Germany's 82 million people.

Conservative governor Volker Bouffier complains that "the election campaign has been completely overshadowed by Berlin." Social Democrat challenger Thorsten Schaefer-Guembel says that "we are experiencing a crisis of confidence — that has a lot to do with the fact that too much waffling is going on and too little being done."

Voters appear generally satisfied with Bouffier's government, the first coalition between the CDU and the traditionally left-leaning Greens to last a full parliamentary term, and an unexpectedly harmonious alliance.

But only the Greens, who are in opposition nationally, are benefiting in polls.

Recent surveys have shown support of up to 28 percent for the CDU and up to 21 percent for the Social Democrats, down from 38.3 and 30.7 percent respectively in a 2013 vote. They show the Greens as high as 22 percent, up from 11.1 percent five years ago.

Gains are likely for other smaller parties, and the far-right, anti-migration Alternative for Germany appears set to enter the last of Germany's 16 state legislatures with support of up to 13 percent. The party entered the national parliament last year and, along with the Greens, has benefited from the federal government's disarray.

Such results would make various regional coalitions possible, with the Greens potentially joining parties to their right or left or even, if their results are exceptionally good, having a chance at making local leader Tarek Al-Wazir — currently Bouffier's deputy — the state governor.

Observers believe Bouffier losing power, or a disastrous result for Schaefer-Guembel, would further destabilize Merkel's federal coalition. The two men are deputy national leaders of their parties.

A loss for Bouffier would make life more difficult for Merkel, who has indicated that she plans to seek another two-year term as CDU leader at a congress in December. The government's frailty has weakened her, as has the ouster of a close ally as leader of her party's parliamentary group.

The Social Democrats only reluctantly entered Merkel's national government in March, and many are dismayed by what has happened since. A very poor performance in Hesse could embolden critics to push for the Social Democrats to leave the federal coalition, and endanger the job of party leader Andrea Nahles.

The government has been through two major crises, first over whether to turn back small numbers of migrants at the German-Austrian border and then over what to do with the head of Germany's domestic intelligence service after he was accused of recent downplaying far-right violence against migrants. It has failed to convince voters that it's achieving much on other matters.

"If this government were to break apart now, it would come down to early elections," CDU general secretary Annegret Kramp-Karrenbauer said this week.

She argued that the three governing parties should instead, after the Hesse vote, prioritize a few policies to concentrate on implementing as "an important signal" to Germans.