BERLIN — Germany's parliament is expected to vote Friday on an opposition bill calling for tougher rules on migration that could become the first legislation to pass thanks to a far-right party — adding to a controversy about the attitude of the front-runner in Germany's upcoming election toward the far right.

German conservative leader Friedrich Merz on Wednesday defended his controversial migration reforms after stinging criticism from Chancellor Olaf Scholz, ahead of votes on two motions that could pass with the support of the far-right Alternative for Germany (AfD).

Former German Chancellor Angela Merkel has issued rare public criticism of her successor as the country’s center-right leader, the front-runner in Germany’s election next month, for putting to parliament proposals for tough new migration rules that only passed with the help of a far-right party.

Germany’s parliament has narrowly approved a call by Chancellor Olaf Scholz’s main challenger to turn back many more migrants at the country’s borders, with the help of a far-right party.