"We are experiencing the end of the second big national party in Germany: the CDU cannot reconcile its opposing factions any longer after the SPD failed to do the same thing," Sigmar Gabriel told the German daily Bild.
Gabriel, who used to preside over the Social Democrats (SPD), said that a second leadership contest in the governing CDU-SPD coalition after the latter’s vote in November "paralyzes" the government.
"I believe it will not be long until a new election is called," he said.
Annegret Kramp-Karrenbauer said she would quit as CDU leader and would not run for chancellor at the next federal elections. The announcement comes after her row last week with the party’s branch in Thuringia, which aligned with the right-wing AfD to oust a leftist state premier.
The next national elections are set for 2021. Merkel stood down as CDU leader in 2018, saying she would not seek reelection. Kramp-Karrenbauer took over as party leader months later and was widely expected to seek chancellorship as the two jobs go hand in hand.