BERLIN (AP) -- She enjoys overwhelming popularity and leads an economy that's the envy of Europe. But Angela Merkel is in a fight to clinch a new term for her ruling coalition in Sunday's national election, with polls showing her center-right alliance on a knife-edge as her junior partner's support slumps.
Merkel and her conservative Christian Democratic Union appear likely to fend off a challenge from center-left rival Peer Steinbrueck and emerge as the biggest party in parliament's lower house, whose members choose the chancellor -- making her the strong favorite to win a third term.
But no single party has won an absolute majority in Germany in more than 50 years. And surveys show Merkel's coalition partner, the pro-business Free Democratic Party, has fallen from the nearly 15 percent support it won in 2009 to about the 5 percent needed to keep any seats in Parliament.
If Merkel's alliance falls short of a parliamentary majority, the likeliest outcome is a switch to a Merkel-led "grand coalition" of her conservatives with Steinbrueck's Social Democratic Party, the same combination of traditional rivals that ran Germany from 2005-2009 in Merkel's first term.
That's unlikely to produce a radical change in policies. However, it could signal a subtle shift in emphasizing economic growth over the austerity that Germany has insisted on in exchange for bailing out economically weak European countries such as Greece.
Final results are due within hours of polls closing. But with margins so close, the country could still face weeks of horse-trading before a clear picture emerges about the makeup and policies of Germany's next government.
Merkel's center-right coalition might win re-election but "it will be very tight," said Oskar Niedermayer, a political science professor at Berlin's Free University.
Much may depend on the turnout among the nearly 62 million voters -- about 70 percent four years ago. Political leaders fought Saturday to mobilize their supporters and win over the undecided.
"I'm personally asking people in Germany to give me a strong mandate so that I can serve Germany for another four years, make policies for ... a strong Germany, for a country that is respected in Europe, that works for Europe; a country that stands up for its interests in the world but is a friend of many nations," Merkel said at a rally in Berlin.
Given Merkel's popularity -- polls give her approval ratings of up to 70 percent -- and the economic success enjoyed during what she calls "the most successful government since reunification" 23 years ago, it might seem surprising that the outcome appears so cloudy.
Merkel has won over Germans with her reassuring style, often appearing to be above the political fray. The eurozone's debt crisis has helped preserve her popularity, said Manfred Guellner, the head of the Forsa polling agency.
"She has repeatedly given people the feeling she's taking care that this abstract crisis doesn't rain down on their everyday lives," he said.
Still, it is Merkel rather than her coalition that enjoys sky-high popularity. Voters haven't forgotten public coalition infighting that frequently marred the past four years. Much of the blame went to the Free Democrats.
A new party, Alternative for Germany, which calls for an "orderly breakup" of the euro common currency zone and appeals to socially conservative voters, may sap votes from the governing parties.
State elections in Bavaria last Sunday set off alarms for the Free Democrats, who lost all their seats in the legislature. Since then, they've been angling for votes from Merkel's party since German voters cast two ballots -- one for a specific parliamentary candidate and another for a party.
The Free Democrats were never strong in Bavaria but their disastrous showing gave heart to Merkel's rivals.
"Tomorrow evening, you can be rid of the most inactive, backward-looking, quarrelsome but also loudest-mouthed government since German reunification," Steinbrueck told a rally in Frankfurt Saturday. "We can succeed."
Steinbrueck was referring to government infighting over issues such as the Free Democrats' promises of major tax cuts, which were never realized -- as well as a much-criticized new benefit for stay-at-home parents the challenger pledges to scrap and the government's rejection of a national minimum wage, which he advocates.
Merkel's critics say she has failed to set any direction and presided over policy drift. Steinbrueck --who was once Merkel's finance minister and says he won't serve under her again -- has quipped that if she were in his government, he would give Merkel "the ministry for vagueness."