Although they are careful to play down such talk, the signs are that the Labour candidate Ben Chapman is heading for a spectacular by-election victory in what is regarded as a traditional Conservative seat.
Deputy Prime Minister Michael Heseltine's advance efforts to explain a Conservative defeat as a traditional by-election "kicking" do not disguise the fact that his party is defending a majority of 8,183 in a seat where in the last three general elections their candidate has polled around 25,000 votes - 50 per cent of the turn-out.
Even the Liberal Democrats have started saying there will be no Conservative MP for Wirral South on Friday - knowing privately that the new member will not be their candidate. Unofficial estimates suggest a likely Labour majority of 2,000 to 3,000 on a turn-out of around 65 per cent.
Early in the campaign, the Tory candidate, Les Byrom - bidding to succeed the late Barry Porter - said his biggest fear was apathy. Yesterday, despite the torrential rain and strong wind there was little sign of that - just a smouldering sense of anger at the Government.
Former sales co-ordinator Joan Diamond, 52, a one-time Conservative supporter, made it clear she would be voting on national issues. Mrs Diamond, from Bebington, said she would switch to Labour. "I would rather not vote than vote for the Conservatives. I'm just so dissatisfied with what this government has done." She said she knew a number of other people considering switching from the Tories and is convinced Labour will win - citing the NHS as her prime concern.
Marine engineer Arthur Speed, 51, will also be deserting the Tories today. "They have had 17 years to get their house in order and they haven't done it," he said. He added that he believed a lot of disaffected Tories would return to the fold at the general election, but he would not be among them.
Sandra Grimes, a hairdresser and another former Tory voter, said she would choose either the Liberal Democrats or Labour, adding: "Under the Tories the rich have got richer and the poor have got poorer."
Sylvia Darlington, 60, a wavering Tory supporter, said she was "50-50" on who to vote for, but believed younger voters would switch to Labour this time. "They do not know anything else and they feel it's time for a change." However, in a general election she is uncertain whether she would "risk" another Labour government. "I can remember them [in power] before."
Some Liberal Democrats supporters - whose candidate polled more than 6,000 last time - showed signs that they might vote tactically to make sure the Conservatives lose. Retired pharmacist Mavis Nicholson said she still wanted to vote for the Liberal Democrat candidate Flo Clucas, but added: "If I felt Labour was in danger of not getting in, I will vote Labour."
In the Conservative stronghold of Heswell, the kind of affluent area which has led to descriptions of Wirral South as the Surrey of the North, the Tory vote appears to be holding up better. Pru Pearson, 57, said she would probably still vote Conservative because she liked John Major, but had been tempted to switch. Other staunch Tories said the remembered the high interest rates and economic uncertainty of the 1970s and would stay with their party.
A few others may plump for the "party" which best represents their feelings - there are a total of 12 candidates - but the minority interest groups are unlikely to play a significant role in what is essentially a straight Conservative-Labour fight.
In what has been a fiercely fought campaign, the Labour propaganda machine has come out on top; Ben Chapman posters heavily outnumber the Tory ones around the constituency. Many of the Tory advertisements can be seen around the fields which dot this semi-rural constituency, prompting one local observer to comment that if the cattle and sheep had a vote "the Conservatives would walk home". When the humans have their say, and the vote is announced in the early hours of tomorrow, the Tories are unlikely to be so lucky.