BERLIN (Reuters) - Philipp Roesler offered to step down as leader of Germany's Free Democrats (FDP) on Monday, FDP sources said, a day after his party suffered the worst election result in its history and crashed out of parliament for the first time.
The market-friendly FDP, Merkel's coalition partner between 2009-2013, won 4.8 percent of the vote on Sunday, down sharply from the record 14.6 percent it secured in 2009 and below the 5 percent threshold needed to enter parliament.
As junior coalition partner the FDP had often appeared inept and divided, slumping to ratings of just 2-3 percent and dropping out of a series of regional assemblies.
Vietnamese-born Roesler, who served as economy minister and deputy chancellor in Merkel's center-right coalition, tried to turn things around after taking the helm in 2011.
The party recovered a little ground in 2013 but proved unable to win back enough voters disappointed by its broken promises on tax cuts, and sceptical that they had contributed to Germany's economic success.
(Reporting by Thorsten Severin; writing by Alexandra Hudson, editing by Gareth Jones)