Mr Westerwelle attracted accusations of indecision - and worse - in May 2002 when Mr Moellemann said Israeli Prime Minister Ariel Sharon was more influential in stirring up hatred of Jews than any German anti-Semite and accused the vice-president of Germany's Central Council of Jews, Michel Friedman, of "an intolerant and hate-mongering style" that had the same effect.
Media reports saw Mr Westerwelle as hesitant and weak for being slow in forcing his deputy to apologise and to expel a regional party member who had sparked the controversy by accusing Israel of using Nazi methods against the Palestinians.
The media - and some party members - also suspected Mr Westerwelle of testing the water to see how Mr Moellemann's comments affected the FDP's opinion-poll ratings before deciding which way to jump.
But the scandal appears not to have damaged the party's election chances, and Mr Westerwelle goes into the 2002 election with a strong chance of restoring the FDP to its traditional role as kingmaker between the two big parties.
BBC Monitoring, based in Caversham in southern England, selects and translates information from radio, television, press, news agencies and the Internet from 150 countries in more than 70 languages.