Leader of Merkel's FDP allies keeps party post

German Economy Minister and leader of the liberal Free Democratic Party (FDP) Philipp Roesler reacts as he comments on exit polls of the Lower Saxony state election at the FDP headquarters in Berlin, January 20, 2013.

BERLIN (Reuters) - The leader of Angela Merkel's Free Democrat (FDP) coalition partners, Economy Minister Philipp Roesler, will keep his job as party chief despite offering to quit on Monday following a state election.

But in a sign of unhappiness with Roesler, despite a strong FDP showing in the Lower Saxony vote, a party spokesman said veteran parliamentary leader Rainer Bruederle would take charge of the FDP campaign for September's federal elections.

The FDP has tumbled as low as 2 percent in national polls but defied forecasts it would be ejected from the state assembly in Lower Saxony on Sunday to take 9.9 percent. That was partly due to Merkel's own Christian Democrats (CDU) splitting their ballots to save the FDP.

(Reporting by Stephen Brown; Editing by Noah Barkin)