Chancellor candidate Friedrich Merz and his conservatives slump in poll after far-right backing for migration vote.

The sweat was dripping off Friedrich Merz after the frontrunner to become Germany’s next chancellor saw his bid to outflank an ascendant far right spectacularly backfire in the Bundestag.

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.

The centre-right CDU has been accused of breaking 'taboo' by putting forward a motion to the Bundestag for a stricter migration policy which was backed by the far-right Alternative for Germany party (AfD).

Germany's election frontrunner Friedrich Merz on Monday called on his conservative CDU to "stay the course" after mass protests against its acceptance of far-right AfD support for calls to restrict immigration.