German Chancellor Angela Merkel on Tuesday stressed her determination to ensure that there's no repeat of last year's huge migrant influx as she seeks a new two-year term in charge of her conservative party.

Germany saw about 890,000 asylum-seekers arrive last year, many after Merkel decided in September 2015 to let in migrants who were stuck in Hungary. Numbers have since declined sharply, but Merkel's approach to the migrant crisis has provoked discord within her Christian Democratic Union, 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.

"That was and is our, and my, declared political aim," she said.

While Merkel has continued to insist that Germany will 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 in Germany. Merkel was a driving force behind an agreement between the European Union and Turkey earlier this year to stem the flow of migrants.

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 the CDU.

Tuesday's vote in Essen, where she was first elected chairwoman of the Christian Democratic Union in 2000, offers a test of Merkel's standing with members. Aside from unhappiness about her migrant policy, some members are grumbling about what's perceived as a wider drift to the left during her 11 years as chancellor.

Polls show a solid lead for the conservatives, though their support is well 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.

Merkel is running unopposed for another term at CDU's helm. Two years ago, she won the support of 96.7 percent of delegates, one of her best results.