German Chancellor Angela Merkel on Tuesday stressed her determination to prevent a repeat of last year’s huge migrant influx as she seeks a new two-year term in charge of her conservative party.

She also told a party congress that an immediate priority is to make sure a crisis-shaken Europe doesn’t get any weaker.

Merkel announced last month that she will seek a fourth four-year term as chancellor in an election expected next September. Her springboard to that run is re-election as the chairwoman of her Christian Democratic Union.

Tuesday’s vote in Essen, where she was first elected CDU chairwoman in 2000, offers a test of Merkel’s standing with members. She is running unopposed for another term.

Germany saw about 890,000 asylum-seekers arrive last year. Many came after Merkel decided in September 2015 to let in migrants who were stuck in Hungary. The numbers have since declined sharply, but Merkel’s approach to the migrant crisis has provoked discord within the CDU, which has seen a string of poor state election results this year.

“A situation like the one in the late summer of 2015 cannot, should not and must not be repeated,” Merkel told party delegates at a congress in the western city of Essen.

While Merkel insists that Germany will continue to take in people in genuine need of protection, her government has moved to toughen asylum rules and declare several countries “safe” — meaning people from there can’t expect to get refuge.

Merkel was also a driving force behind an agreement between the European Union and Turkey in March to stem the flow of migrants.

Polls show a solid lead for the conservatives, although their support is still short of the 41.5 percent they won in Germany’s 2013 election. They face new competition from the upstart nationalist Alternative for Germany party, which has thrived by attacking Merkel’s migrant policies.

“The 2017 election will be more difficult than any election before, at least since German reunification,” Merkel said, citing the “strong polarization of our society.”

Merkel told delegates that “parallel societies” won’t be tolerated and advocated banning the wearing of full-face veils used by some Muslim women where that’s possible. But she also hit out at anti-migrant and anti-government protesters who chant “We are the people!” or post hate messages on social media.

“Who the people are … is something that we will all determine, not just a few, however loud they may be,” she declared.

The EU’s longest-serving head of government has often said her aim is for Europe to emerge stronger from crises such as the debt troubles that afflicted the common euro currency.

Merkel said she still believes in that — but “we must in this situation … first do everything so that Europe doesn’t emerge even weaker from the crises than when it went in.”

That “sounds modest, but let’s not deceive ourselves, it is not,” Merkel said, citing conservative icon and ex-Chancellor Helmut Kohl’s maxim that European stability shouldn’t be taken for granted.

Aside from unhappiness about her migrant policy, some party members are grumbling about what’s perceived as a drift to the left during her 11 years as chancellor.

“I have asked a lot of you because the times have asked a lot of us — I am well aware of that,” she said. “And I cannot promise you that there will be fewer demands in the future, because we must do what the times demand of us.”

Still, she stressed Tuesday that the conservatives will rule out tax increases for the next four years.

Two years ago, Merkel won the support of 96.7 percent of party delegates.