Almost one third of a large sample of members who were approached by The Times during the evening at Cardiff University said that they would back Mr Huhne with their first preference vote. A quarter said that they would put Sir Menzies Campbell in first place and Simon Hughes was nearly five points behind him in third. Twenty-six per cent remained undecided.

More significant still for Mr Huhne was the distribution of second preference votes, since he came out well ahead as the second-choice candidate among supporters of Simon Hughes and Sir Menzies.

Despite the number still making up their minds, the survey suggests that Mr Hughes is the most likely to be eliminated after the first round of voting if no candidate achieves the 50 per cent necessary for an outright win. His power base is often assumed to be among party activists, and members attending the Cardiff hustings might have been expected to have a bias towards him, since he was born in Wales and made much of his Welsh links in his opening speech.

The overall findings should be treated with caution, since those participating were active party members who had heard Mr Huhne speak in person, and not “armchair” members who form the majority of this electorate and who are more likely to form an opinion of the candidates based on media coverage. Having entered the Commons only last May after six years as an MEP, Mr Huhne is a lesser-known figure than Sir Menzies or Mr Hughes.

The Welsh Liberal Democratic Party said that the hustings was attended by about 230 of its members. The Times spoke to 174 Lib Dems and asked how they intended to vote. Three were removed from the sample: two because they were attached to candidates’ campaign teams and a third who was not a party member.

Of the remaining 171 members, 52 (30.5 per cent) said that their first preference votes would go to Chris Huhne, 42 (24.5 per cent) to Sir Menzies Campbell and 32 (19 per cent) to Simon Hughes.

The remaining 45, or 26 per cent, were undecided. Several said that they would wait until the candidates had appeared on BBC One’s Question Time tomorrow night.

Sir Menzies is reckoned to be the best-known figure at this stage but if a large number delay voting, Chris Huhne might benefit from having time to raise his profile. Several Lib Dems leaving the hustings told The Times that Chris Huhne had leapt from third to first place as their choice for leader in their minds after hearing him speak.

Daniel Parrott, 31, of Vale of Glamorgan, said: “I was decided on how well he performed. He managed to mix humour and strong political direction.”

Charlie Pearcy, 51, of Cardiff, said: “Huhne went from third to first, basically because of his commitment to electoral reform.”

Although The Times survey is not representative, it is a significant attempt to gauge the views of a large number of Liberal Democrat members. Thousands will be attending hustings such as the one on Monday before ballot papers must be returned on March 1. Traditional polling companies must make thousands of telephone calls to identify a statistically significant number of Lib Dem voters. It is also the first time the voters’ second preferences — which could decide the election — have been examined.

The survey team: Tamara Cohen, Charlotte Newton

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