Tories were warned not to expect a direct boost in support from Chris Huhne's fall from grace as they unveiled their candidate for the Eastleigh by-election.
Maria Hutchings, who failed to topple Huhne in 2010, will fight the seat again after a guilty plea to dodging a speeding penalty ended the ex-cabinet minister's political career.
Conservative Party chairman Grant Shapps and Mrs Hutchings both spoke about ''trust'' ahead of a weekend blitz in what promises to be a brutal battle with their Liberal coalition partners.
Deputy Prime Minister Nick Clegg had earlier urged voters not to exact retribution for his former leadership rival's disgrace as the party moved the writ in the Commons for a February 28 poll.
But former Tory Treasurer Lord Ashcroft warned his party that though it started the contest in the lead, his polling suggested few voters were likely to ''switch out of disgust''.
The survey conducted for the peer in the immediate wake of Huhne's resignation put the Tories on 34%, with Lib Dems on 31%, Labour on 19% and Ukip fourth with 13%.
Sources said the Tories were preparing a ''big push'' in the Hampshire town tomorrow when local Lib Dems are due to meet to select the party's own candidate.
It is defending a 3,864 majority.
Mr Shapps - who has previously declared the people of Eastleigh were ''sold a lie'' by Huhne - hailed Mrs Hutchings as someone ''people in Eastleigh can trust''.
Huhne - the MP since 2005 - consistently denied avoiding a driving ban by getting his wife to accept penalty points before changing his plea to guilty Mrs Hutchings, first thrust into the limelight in 2005 when she challenged then prime minister Tony Blair during a TV debate over a special school closure, said: ''We need a local MP we can trust - someone who will support people who work hard and do the right thing''.
She added: ''Although I may not be a professional politician, I'm a straight-talking businesswoman and mother of four who lives in the local area.''
Mr Clegg said: ''I think the choice for the people of Eastleigh in the by-election is what kind of an MP do they want to have now.
''I hope that it will be on that basis rather than in a mood or spirit of retribution that the debate will be conducted in Eastleigh.''
He sought to draw a clear distinction with his Westminster coalition partners by highlighting the Lib Dem commitment to a 1% annual ''mansion tax'' on £2 million-plus properties to fund tax cuts for ''hard-pressed families'' - a proposal the Tories have consistently rejected.
Labour sources are hoping for a strong showing, but privately accept they have little chances of winning despite being nine points up on their 2010 showing in the Ashcroft-commissioned poll.
The figures represent a fall of almost 16 points in Lib Dem support since the 2010 general election, when Huhne scooped 46.5% of the vote.
Tories are down five points since the election and Labour and Ukip both up nine.
Lord Ashcroft, a major Tory donor who was deputy chairman of the party until 2010, said the poll suggested both coalition parties have ''everything to play for''.
While Tory voters were the most committed to the party and the party was most likely to attract wavering Lib Dems, Labour voters were the most open to switching and preferred the Lib Dems.
And two-thirds of those taking part in the poll agreed that ''the Lib Dems do a good job locally in my area'', where the party dominates the local council with 40 out of 44 seats.
''Huhne was a popular and, by all accounts, assiduous MP, and many in Eastleigh will be sad to see him go and circumstances of his departure,'' Lord Ashcroft cautioned.
''The Tories should not expect many to switch out of disgust,'' he added, predicting a ''bruising - but fascinating'' contest.
John Denham, Labour MP for the neighbouring Southampton Itchen constituency, said: ''In this campaign the Lib Dems and the Conservatives will try to blame each other for what's gone wrong.
''Only by voting Labour can Eastleigh people reject a Conservative-Liberal Democrat Government that cuts taxes for millionaires and doesn't understand how tough life is for local people.''
:: Some 1,006 adults were interviewed by telephone in the Eastleigh constituency on February 4 and 5.