Updated

Germany's center-left Social Democrats are debating the party's future leadership following a week of vicious infighting that has overshadowed a coalition deal reached with Chancellor Angela Merkel's conservative Union bloc.

Since agreeing last week to join a government with Merkel, senior Social Democrats have fallen out over the distribution of ministerial posts.

Chairman Martin Schulz is expected to step down Tuesday and make way for parliamentary caucus leader Andrea Nahles, a move strongly opposed by some in the party.

The internal dispute within the party has increased concerns that its leadership could fail to rally members behind a grassroots vote on whether to enter into a "grand coalition" with Merkel.

If members reject the coalition, Merkel's only realistic options would be to form a minority government or seek fresh elections.