Mr Campbell, the party's foreign affairs spokesman, levelled the charge against his fellow MPs as he called for the field to be narrowed from the seven at present to just two or three candidates.
In a scathing assessment of some colleagues, the MP for Fife North East, who pulled out of the race recently, made clear he believed that some were not suitable to replace Paddy Ashdown in the top job. "Ambition has overtaken realism to some extent in this contest," he told Breakfast with Frost on BBC television.
The leadership battle has seen six hopefuls throw their hats into the ring since Friday: Charles Kennedy, Jackie Ballard, Simon Hughes, Don Foster, Malcolm Bruce and David Rendel. The party's chief whip, Paul Tyler, has also indicated he may stand.
Some of the candidates, particularly Mr Bruce, Mr Rendel and Mr Tyler, are regarded as having little chance of success and have been urged to pull out to prevent the contest descending into farce.
In a clear reference to Ms Ballard's frenetic campaign to become leader, Mr Campbell said that he would wait to see who finally declared before backing one candidate.
"There's a lot of talk, a lot of people dashing around the country in helicopters and other things, but I want to wait and see who's actually in the field," he said. "There are clear qualities for the leader of the Liberal Democrats: Parliamentary experience, political courage - which Paddy Ashdown obviously had - good judgement and personality.
"And I think some of those who have put themselves forward are perhaps making rather optimistic judgements about the extent to which they possess all of these qualities."
Ms Ballard suggested that some of her rivals would drop out before nominations close later this month. She told GMTV's Sunday Programme. "I'm not putting pressure on anyone but I don't suspect all seven will run." The Taunton MP made clear the party would remain "independent" under her leadership and would never merge with Labour.