Fractures broke out in the far-right AfD (Alternative for Germany) this week, just days after becoming the country’s third largest political party in a record election showing.
Co-leader Frauke Petry and her husband Marcus Pretzell, a high-ranking regional leader, confirmed they were leaving the party, accusing it of being “anarchic” and unfit to form a future German government.
The AfD won 94 seats in the federal parliament, including Ms Petry’s, with 12.6% of the vote.
But Ms Petry stunned colleagues on Monday by dramatically walking out of a party press conference held to celebrate the election result.
“It's clear that this step is coming,” she told German news agency DPA when asked if she was leaving the party.
She later told Die Welt: “My decision is based exclusively on my not very optimistic view of how the AfD is likely to develop.”
Hours later, four AfD MPs in the Mecklenburg-Vorpommern regional parliament also resigned.
Chancellor Angela Merkel won a fourth successive term in Sunday’s election, but will have to assemble a much less stable government after the Social Democrats, her former partners, said they would return to opposition and not resurrect a grand coalition with her.
Ms Merkel’s coalition is likely to include the Green Party and the business-friendly Free Democrats.