Friedrich Merz, the conservative frontrunner in the German election, will focus his campaign on proposals to revive the struggling economy after a bruising clash last week over tougher immigration rules.

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.

Merz, leader of the Christian Democrats, had sought to restrict immigration rules with the support of the Alternative for Germany (AfD) party. The bill fell short of 12 votes on Friday. Twelve MPs from Merz’s parliamentary group were absent.