Germany's influx of asylum seekers fell by about two thirds in 2016, handing Chancellor Angela Merkel an election-year argument against critics of her open-borders policy.

An estimated 280,000 refugees entered Germany last year, compared with 890,000 in 2015, Interior Minister Thomas de Maiziere told reporters on Wednesday. After a large influx during the first three months, the flow slowed to fewer than 17,000 in December, according to government data. More than half came from Syria, Afghanistan or Iraq.

"It is possible to control the influx and to reduce it," de Maiziere said in Berlin.

Merkel's central promise at the peak of Europe's refugee crisis in late 2015 was to "noticeably reduce" the number of arrivals. She's running for a fourth term this year with an additional pledge that the events of 2015, when Germany took in the bulk of a record number of migrants fleeing conflicts in Syria, Iraq and beyond, will never be repeated.

As Merkel is assailed by the anti-immigration Alternative for Germany party, the lower numbers may also help her in a dispute with her Bavarian allies in the Christian Social Union, which is insisting on a migration cap. Merkel rejects that as inconsistent with Germany's obligations and legally unworkable.

While Merkel has insisted on Germany's legal and moral responsibility to welcome migrants, a cascade of border closures from Austria to Greece early last year blocked the main Balkan route to Germany. Last March, a European Union accord with Turkey, spearheaded by Merkel, sealed the sea route for refugees into Europe over the Aegean Sea.

The chancellor's Christian Democratic-led bloc got a start-of-the-year poll boost, climbing two percentage points to 38 percent in a survey for the Bild am Sonntag newspaper, her highest level in a year. The Social Democrats, her junior coalition partner, were at 22 percent.

The refugee crisis has stirred an emotional debate in Germany and a populist backlash that diminished the chancellor's popularity. Her coalition agreed on measures this week to tighten migration rules after a Tunisian national, whose asylum application had been rejected, was identified as the suspect who drove a truck into a crowded Berlin Christmas market last month. Twelve people died in what authorities called a terrorist attack.

While Merkel says on the campaign trail that migrants who don't qualify for asylum must leave Germany, the 2016 data show how daunting that task may be. Some 80,000 asylum seekers left last year, 55,000 of them voluntarily and 25,000 through deportation, de Maiziere said.