John Curtice: Labour bid to save face, the Tories bid to save their leader

Two key questions hang over the English local elections that are taking place almost everywhere outside London tomorrow. Will the Conservatives do well enough to enable Iain Duncan Smith to avoid a challenge to his leadership? And will Labour benefit from a Baghdad bounce and so reaffirm Tony Blair's authority over his party? Alas, the answer to both questions is shrouded in misinformation and misunderstanding.

It all started when the Conservatives suggested before Christmas that they could only be expected to make net gains of 30 seats – even though more than 10,000 seats are at stake in what is the biggest year in the four-yearly local election cycle. The claim was repeated by Mr Duncan Smith on Sunday. And at first glance the reasoning is impeccable – they made a record 1,300 gains in 1999 when most of the seats were last contested, so they cannot be expected to make any further advance this time around.

In truth the Conservatives' target exhibits a remarkable poverty of ambition. For all that happened in 1999 was that the party partly recovered from its record worst local election performance in 1995 when it lost nearly 2,000 seats. When projected into the equivalent of a nationwide general election performance – as the BBC will do again tomorrow – the Conservatives were still as much as three points behind Labour in the popular vote. An opposition on the road back to power, however, is one that comfortably leads the government of the day in local elections.

This grudgingly seems to have been accepted by Central Office, which in private at least is now willing to acknowledge the party might be expected to make a couple of hundred gains. But even this would still mean that the Conservatives had not recovered all of their 1995 losses and would probably imply a projected national vote of no more than 35 per cent. Even William Hague managed a projected vote of 38 per cent in the 2000 local elections, just 12 months before the Conservatives crashed to a second record defeat. In truth even 200 net gains means no more than treading water.

Failure to make a real advance would, however, seem to have a ready-made excuse – a "Baghdad bounce" in Mr Blair's favour. And indeed Labour's position in the polls appears to have improved.

Yet in truth Labour's recent poll gains are more of a rebound than a bounce. Before the Iraqi war Labour was experiencing its worst run of poll ratings since Tony Blair became leader. Its rating has now simply returned to where it was just before Christmas. But that still leaves it three points down on where it was this time last year, let alone at least eight points below where it was four years ago. In short, even if Labour has gained from the conflict in the Gulf there still seems to be plenty of scope for Conservative gains tomorrow – and Labour losses. The party's control of a number of big councils – Bristol, Bolton, Derby, Leicester, Trafford and maybe even Birmingham – could be at stake.

Labour has a particular problem of its own – it consistently does less well in local elections than when Westminster elections come around. Its projected share at each annual round of local elections is commonly more than 10 points below its standing in the polls. So with a current poll rating of no more than 42 per cent, Labour's projected share this year could well fall below 30 per cent. Meanwhile, possible disaffection among Muslim voters and loss of support to the BNP in some white working-class communities can only add to Labour's difficulties.

Still the gap between Labour's local vote and its national popularity only emphasises that anything much less than a double-digit Conservative lead in the projected vote – and thus Conservative seat gains well in excess of 500 – will be insufficient to convince that the Conservatives have become a credible alternative to Labour. At the same time the gap leaves Mr Blair vulnerable to the embarrassment of being overtaken by the local election party par excellence, the Liberal Democrats.

Charles Kennedy did not have a good war and the Liberal Democrats' poll rating has fallen back. But at 21 per cent, his party is still at least four points up on where it was four years ago, potentially enough forhundreds of net gains from both Labour and the Conservatives. And as the party regularly wins some 10 per cent more of the projected national vote in local elections than its poll rating it could mean pushing Labour into third place for the first time. That would at least be a reality check for the Government.

John Curtice is professor of politics at Strathclyde University