German conservative leader Friedrich Merz is set to take his hard-line immigration push to the next level despite a growing backlash over his move this week to force a resolution through parliament with backing from the far right.

Germany's opposition conservatives won parliamentary approval on Wednesday for a proposal to drastically restrict migration with the help of votes from the Alternative for Germany (AfD), breaking a taboo on cooperation with the far-right.

Germany's conservative opposition leader was set Friday to again seek far-right support in parliament on the flashpoint issue of immigration, after his first effort sparked widespread condemnation and street protests.

The German Catholic and Protestant churches warned on Tuesday against the conservative opposition's plan to crack down on immigration, which they said could break a convention against mainstream parties cooperating with the far-right.

Protesters in Germany on Thursday rallied against the conservative CDU party to decry its cooperation with the far-right AfD in pushing through parliament a motion to demand a crackdown on immigration.