The public usually makes up its mind about party leaders within a year or so of them being elected, and such opinions are then very hard to shift. Voters took a negative view of William Hague in 1998-99 and Iain Duncan Smith in 2002-03, and there was nothing they could do about it. That is the dilemma facing Sir Menzies Campbell and his party now.

The latest Populus poll for The Times makes grim reading for Sir Menzies. The Lib Dems are now on 17 per cent, down three points since mid-April. This is the lowest since Populus started polling for The Times in January 2003, though the party had lower midterm ratings before successes in 1997 and 2001.

Moreover, on a leader rating scale of 0 to 10, Sir Menzies is now on 4.2, down 0.45 since January, and by far the lowest rating for himself and Charles Kennedy. Only Mr Duncan Smith has received lower ratings since 2003, with a range of 4.00 to 4.35. Among the reduced band of Lib Dem voters, his rating is 5.37, by far the lowest of the party leaders, and worse than Mr Kennedy’s low of 6.30.

Even among Lib Dem voters, just 4 per cent rate him as strong compared with Messrs Blair, Brown and Cameron, and just 8 per cent charismatic. Voters generally think the Lib Dems would do better getting rid of Sir Menzies rather than keeping him, by a 45 to 33 per cent margin. Even more worrying is that 54 per cent of Lib Dem voters want him to go, and just 39 per cent to stay.

But how far is Sir Menzies himself the problem? He is not a trendy figure. But his strengths of authority, shrewdness and judgment should not be underestimated. He has steadied the Lib Dems after the Kennedy implosion only 16 months ago. The party rating could easily have slipped to the low teens. He has provided a firm lead for a wideranging internal policy review, and his shadow team like working with him.

Moreover, all is not gloom and doom for the Lib Dems. The local elections on May 3 were poor as the party faced a Tory squeeze in the South and made only patchy progress against Labour farther north, but the results are not universally as bad as they first looked. Three fifths of the losses were in only ten councils and the party did well in some parliamentary seats won in 2005, such as Westmorland & Lonsdale, Bristol West, Cambridge, and Leeds North West, and in some Labour-held target seats such as Hull North and City of Durham.

The real question is whether the low-key, substance-over-style approach of Sir Menzies can be sustained in the run-up to a general election, or whether the party will face a further squeeze.

It is far from clear that any alternative leader would necessarily do better. Chris Huhne and Nick Clegg might be seen as more energetic, but both would have to establish their authority and could be accused of inexperience, since they were first elected to the Commons only two years ago. There seems little appetite for another leadership election and all the upheavals that involves. Sir Menzies is not under pressure to stand down. But the Lib Dem fear is that voters have made up their minds about him, and are not listening to what he has to say.

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