As the autumn conference season starts, The Times publishes the first of a series of polls about the image and characteristics of the main parties. The poll, based on interviews with 1,007 adults between September 8 and 10 (for more details go to www.populuslimited.com), suggests that, although support for the party remains pretty stable at about 20 per cent and it is doing well in by-elections, there are serious underlying weaknesses.

In particular, Sir Menzies has yet to convince the public that he is the right leader. His rating on the Populus leader index (on a 0 to 10 range) is lower than Charles Kennedy, his predecessor (at 4.47 against 5 for the latter last autumn) and is declining. Moreover, his rating has fallen further among Lib Dem voters and is the lowest of the three party leaders among their own supporters. The new poll shows that more Lib Dem supporters than voters generally (51 to 47 per cent) think that the party “made a big mistake in choosing Campbell to replace Kennedy”. Although the number of Lib Dems in the sample is small, the trend is clear.

The leadership turmoil last winter has done serious damage to the party’s image. The number believing that the party is united has dropped from 71 to 46 per cent since September last year, and those thinking that it has a good team of leaders from 52 to 32 per cent. Even where the Lib Dems are still ahead of the other two parties, such as “understanding the way people live their lives in today’s Britain”, agreement has dropped sharply, from 55 to 43 per cent in the past year. The Lib Dems are still seen as more honest and principled than the other two main parties, but, here too, agreement is down from 52 to 41 per cent.

There is an important positive in that half the public (51 per cent) think that the Lib Dems are “now a credible alternative to Labour because of their policies to redistribute wealth and on green issues”. The only policy issue where the Lib Dems are seen as the best party remains “tackling the problem of global warming”.

There has been virtually no change over three years in the roughly three fifths of voters who think that the Lib Dems are “basically a protest vote party because they have no real chance of winning”. This includes just under two fifths (37 per cent) of Lib Dem voters.

The general image remains “nice but woolly” and two thirds of voters (66 per cent) say that the Lib Dems “seem decent people but their policies probably don’t really add up”.

The poll also highlights the party’s vulnerability to changes at the top among the other parties. Nearly half of Lib Dem voters (49 per cent) say “Labour will be more attractive to me once Tony Blair has gone”.

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