Polling drama as campaign starts

ANALYSIS David Cowling Editor, BBC Political Research

Whatever else may be said for or against opinion polls, the crop of four released on 5 April has added some excitement to the start of the campaign.

Three (ICM, NOP and Populus) produced Labour leads of between 2-3% and one (MORI) gave a 5% Conservative lead.

If we average these four polls and compare the resulting figures with the average of the March surveys by the same pollsters we find Labour down three points to 36%; the Conservatives on 35 (34 in March) and the Lib Dems on 21 (20 in March).

So far, it seems that the closeness of the race is due to Labour votes drifting to other parties rather than transferring to the Conservatives.

Likelihood to vote

MORI's five point Conservative lead is the biggest they have registered for the party since 1992. However, this poll illustrates one of the key issues of this election.

POLL TRACKER See who's up and who's down in the polls since January Poll tracker

Among all respondents in the MORI survey, Labour has a lead of 5%. The much publicised Conservative lead resulted when only those who said they were "absolutely certain to vote" were included.

If all those naming a party were included, MORI's figures are Con: 33%; Lab: 38%; LD: 23%; others: 6%. This difference suggests that Conservative supporters are more determined to get out there and vote.

The ICM, NOP and Populus figures suggest swings of between 3-3.5% from Labour to the Conservatives since the last election.

If such a uniform swing were to take place Labour would be left with a majority of around 90 seats.

MORI's poll suggests a swing of around 7% since 2001, which would probably leave Labour as the largest single party in a hung parliament.

Long term

Looking back over polls since the last general election, Labour's lead over the Conservatives has narrowed significantly.

They held comfortable double digit leads until the autumn of 2003 but saw them decline significantly through to the autumn of 2004.

In recent months their poll lead has increased but nowhere near the levels they achieved in the run-up to the 2001 election.

The Conservatives have struggled in the polls to match their 33% share of the vote in the 2001 election. In the first three months of 2005, the monthly average of voting intention polls put them in no better position than four years ago.

However, they will be encouraged that most polls - like Tuesday's MORI poll - show a greater determination among Conservative supporters to turn out on election day than among Labour or Lib Dem supporters.

The Lib Dems will be encouraged that for much of the past four years their poll ratings have been consistently higher than in recent elections.

Understandably, they use these improved poll figures to claim that they will increase their crop of seats in this election.

What they have to take into account is that the polls also suggest that Lib Dems are the least inspired to vote among the supporters of the main parties.