I'm going to keep seat, says Clegg
Nick Clegg said he was confident of remaining an MP despite a poll putting Labour ahead by two points in his constituency.
A defiant Liberal Democrat leader said: "I'm going to win."
The Deputy Prime Minister, who is defending a healthy 15,284 majority in Sheffield Hallam, trails by 27% to 29%, according to the latest research by Lord Ashcroft.
It is the latest in a series of polls to suggest Mr Clegg faces a struggle to win back voters critical of his decision to lead the party into coalition with the Conservatives and abandon a promise not to raise student tuition fees.
But as he took the national campaign to Scotland, he said: "I'm confident - not complacent but confident - that we're going to win. That's what our own polling and our canvass returns show."
Mr Clegg said he would be knocking on doors in his constituency over the Easter weekend.
He said: "On May 7 I will be returned as MP for Sheffield Hallam, which is one of the greatest pleasures of my public life."
The polling found evidence of a concerted effort on the ground to prevent the Deputy Prime Minister being ousted, with more than three-quarters saying they had received literature, letters, phone calls or visits from his team.
That was significantly more than for other parties.
And in a finding that further fuelled speculation that Mr Clegg's chances were being bolstered by his former coalition partners, the Conservatives appeared to be doing little active campaigning in his seat.
Only 13% of voters said they recalled having any contact from the party.
Just over 1,000 people in the South Yorkshire constituency were interviewed by telephone between March 22-28 and asked to say how they would vote.
Better news for the party in the survey of eight Lib Dem battleground seats concerned Cambridge, where it has moved nine points ahead of Labour in the battle to retain the seat - after being a point behind in a similar poll in September.
The Lib Dems have also fallen further behind the Tories in both North Devon and St Austell & Newquay, where one-point deficits have become seven and six respectively - spelling danger for ex-minister Nick Harvey and Stephen Gilbert.
But in three other of its South West seats - North Cornwall, St Ives and Torbay - it has edged into slight leads.
Lib Dem sources stressed that Lord Ashcroft's poll did not name the candidates and insisted that the party did 9% better in polls where individuals were named and "clearly Nick is extremely well known in Sheffield Hallam".
The party also pointed to local election results within the constituency, where in 16 contests since 2010 the Liberal Democrats have won 14.
Mr Clegg remains bookies' odds-on favourite to retain the seat but a flurry of bets have seen him go out from a 1/3 to a 1/2 shot with William Hill - with Labour 6/4.
Spokesman Graham Sharpe said: "Political punters are betting Mr Clegg will be clogged and cleared out of Parliament."