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Chancellor Angela Merkel's conservatives face possible ejection from Berlin's state government in an election this weekend, while a nationalist party hopes for more gains at the expense of Germany's traditional political forces.

Sunday's vote comes two weeks after Merkel's Christian Democratic Union was beaten into third place by the nationalist Alternative for Germany, or AfD, in the eastern state of Mecklenburg-Western Pomerania, where Merkel has her parliamentary constituency. The CDU has long been weak in Berlin but another feeble result, though not immediately dangerous to Merkel, would keep up political pressure on the chancellor.

Merkel's opening of Germany's borders to migrants last year featured prominently in Mecklenburg, although the influx has diminished drastically. The result there prompted her allies in Bavaria, the Christian Social Union, to step up a drive for tougher refugee policies — an internal dispute that isn't helping the conservatives' poll ratings.

Merkel has defended her approach and, at a rally Wednesday, criticized opponents "who think that if you provoke, if you have snappy slogans ... problems will solve themselves."

"It is not enough ... to know who is to blame, it is not enough just to know what you're against," she said. "We need good solutions that hold our society together."

Local issues are more prominent in Berlin, a city of 3.5 million. That isn't good news for the governing parties: disillusionment is high over the capital's notoriously inefficient bureaucracy and issues such as years of delays in opening its new airport.

Mayor Michael Mueller's center-left Social Democrats lead the local government, with Merkel's CDU as junior partner, a bad-tempered alliance of Germany's biggest parties similar to Merkel's national governing coalition. Mueller says he wants to dump the conservatives for one or more left-leaning partners.

"It looks as though both big parties ... will probably do even worse than last time," said Manfred Guellner, the head of the Forsa polling agency, referring to Berlin's 2011 state election when both were already weak. Voters consider CDU mayoral contender Frank Henkel, like his counterpart in Mecklenburg, an "extremely weak" candidate, he said.

He argued that it suits local leaders to blame the chancellor for the result in Mecklenburg, but only AfD supporters were motivated by the desire to punish Merkel. "They now hate Merkel; for them, national politics are more important than local politics, and the refugee question more important than for all other voters."

As for the effect on national politics, he said "there are always dents" in support immediately after poor results, but they can be ironed out.

Polls suggest that the governing parties may not win a combined majority in Berlin's state legislature, which elects the mayor. That already happened earlier this year in the eastern region of Saxony-Anhalt. It's a novel situation in Germany, caused in part by a long-term erosion of voter loyalty but in particular by AfD's rise.

In Berlin, the conservatives have stressed law-and-order issues, with Henkel, the current state interior minister, also leading calls for a ban on face-covering veils. The governing parties have accused each other of not taking sufficient responsibility for the refugee situation after Berlin's initially chaotic handling of it last year.

The low-key Mueller succeeded long-serving predecessor Klaus Wowereit in 2014 after he stepped down in mid-term. Even under the charismatic Wowereit, the Social Democrats won a lackluster 28.3 percent of votes five years ago, followed by Merkel's party with 23.3 percent.

Polls suggest their support will sink to at most 24 percent and 19 percent respectively. The opposition Greens and Left Party, potential new partners for Mueller, are a few points further behind.

The three-year-old AfD is confident, plastering Berlin with posters proclaiming "First Schwerin, now Berlin!" Schwerin is Mecklenburg's state capital. Still, co-chairwoman Frauke Petry cautions that Berlin "is a significantly more difficult environment to campaign in."

Polls show its support at up to 15 percent in Berlin. The capital is somewhat less promising territory than rural Mecklenburg, where it won 20.8 percent to finish second.

Berlin's 9.7 percent unemployment rate is well above the national average of 6.1 percent, but it also has large immigrant communities and an international outlook.

In the Berlin campaign, led by former army colonel Georg Pazderski, AfD has hammered home its opposition to Merkel's insistence that "we will manage" the challenge of integrating migrants.

Pazderski has said Germany should "train, but not integrate" refugees, preparing them to go home.

Mueller wrote on Facebook Thursday that 10-14 percent support for AfD would "be viewed in the whole world as a sign of the comeback of the right and Nazis in Germany."

The Berlin vote comes about a year before a national election in which Merkel is widely expected to seek a fourth term, though she still hasn't declared her hand. Three more state elections follow next spring.

Polls show nationwide support for AfD of between 11 and 14 percent. Last weekend, however, it polled only 7.8 percent in municipal elections in the western state of Lower Saxony.

That suggests "AfD's anchorage in the electorate isn't far enough along yet that we can talk about an established party," Guellner said.