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 likely next chancellor wants tougher migration measures even with AfD support, triggering a fierce pre-election debate.

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).