BERLIN - A senior leader of Germany's Free Democrats resigned unexpectedly on Wednesday in the latest sign of turmoil in the party that shares power with Chancellor Angela Merkel's conservatives.

Christian Lindner, general secretary of the beleaguered FDP and a rising star who many wanted to see take over as chairman, stepped down in a move which appeared to be linked to the poor turnout in a party referendum on euro zone rescue moves.

The resignation points to deep splits in the party over whether to support Merkel's efforts to shore up weak euro zone members, and could destabilise her coalition if these widen.

"He lost his nerve," a senior FDP official told Reuters when asked about Lindner's move. Lindner, 32, had responsibility for organising the referendum which was forced upon the party leadership by a group of eurosceptics within the FDP.

His departure is the latest setback for the FDP, a pro-business party whose support has fallen to just 3 percent in opinion polls after it won a record 14.6 percent in the 2009 election, helping Merkel secure a second term.

The normally loquacious Lindner made a short statement to journalists at FDP headquarters in Berlin, but then left without taking questions, saying only "Auf Wiedersehen".

"There comes a time when you have to make room to allow for a new dynamic," said Lindner, a polished speaker who previously worked in the advertising industry. "The events in recent weeks and days have strengthened my belief that this is the case."

Angry that the FDP leadership was backing Merkel's euro rescue moves, eurosceptics led by lawmaker Frank Schaeffler led a campaign in recent months to collect signatures within the party for the referendum, which is non-binding.

Their idea was send a signal to the leadership by showing them that grass-roots FDP members opposed euro rescue moves.

The referendum, whose results are expected to be published on Friday, is unlikely to pass because the required quorum of FDP members is not expected to be reached.

Of the 64,000 members of the party, 21,000 needed to take part for it to be valid.

The failure to reach a quorum would cast a poor light on Lindner, who was charged with organising the voting.

FDP executive board. He also came under fire for calling Schaeffler "the David Cameron of the FDP" because he wanted to isolate the party in Europe.

Political scientists say many FDP members may have shunned the vote because they actually support the euro sceptics' views but did not want to directly damage the FDP leadership.

Lindner married a newspaper reporter in August. He also obtained a license to drive racing cars two years ago.