The state of the economy and the imposition of VAT on domestic fuel bills are the main reasons given by voters intending to desert the Tories in favour of the Liberal Democrats on Thursday.
A poll by NOP for the Independent on Sunday, carried out on Thursday and Friday, suggests that the Tories will lose Christchurch, one of their safest seats, on a 35 per cent swing, thus eclipsing nearly all the great post- war by-election upsets. Only Simon Hughes's victory for the Alliance in Bermondsey in 1983 has recorded a higher swing. But that was against Labour, then in Opposition. The Government lost the Newbury by-election to the Liberal Democrats last April on a 28 per cent swing.
The opinion poll result, it must be stressed, may not be repeated on Thursday. By-election polls are subject to more than usual error - a similar poll, the weekend before Newbury, greatly underestimated the Liberal Democrat success.
Our poll has barely a crumb of comfort for the Tories. The large majority - 72 per cent - of those planning to vote Liberal Democrat on Thursday say they would do the same if it were a General Election. Of those who voted Tory last year but intend to vote Liberal Democrat in the by- election (the 'Tory deserters'), only 17 per cent say they would definitely switch back to the Government in a another general election. Another 18 per cent were undecided.
Further, a change of leader would hardly help the Tories at all. Asked if the accession of Kenneth Clarke, the Chancellor, to the Conservative leadership would make any difference to their vote on Thursday, 88 per cent of the Tory deserters said it would not; 84 per cent said it would make no difference if Douglas Hurd, the Foreign Secretary, were leader. Only the return of Margaret Thatcher would make a significant difference to the Tory vote - though nothing like enough to affect the result. Twenty-one per cent of the deserters say they would return to the Tories if she were leader.
Voters were asked to choose two from a list of 10 possible factors influencing their vote on Thursday. Among Tory deserters, 44 per cent said the overall state of the economy was an important influence and 43 per cent chose VAT on fuel. Law and order and the Government's general competence were the next most important influences. Mr Major's leadership was well down the list; only rail privatisation and Tory divisions on Europe were less important.
The poll enables Mr Major's supporters to argue that voters will return to the Tory fold once they feel the benefits of improved economic performance and that a change of leader would make no difference either way.
For Labour, the poll is in some ways as discouraging as for the Tories. Only five per cent say they intend to vote Labour on Thursday - in the General Election, the party got 12 per cent of the vote.
NOP interviewed a representative quota sample of 768 adults aged 18-plus across the whole constituency of Christchurch on 22 and 23 July.