In the past, the party has been wary of saying how many seats it hoped to get and Paddy Ashdown has resolutely refused to speculate, but last night Lib- Dem peer Baroness Williams said: "My prediction is somewhere above 40. I have even put a bet on that."
She told a reporter from BBC 2's Newsnight programme: "I think it would constitute a breakthrough because, don't forget that we are holding every one of the by-election victories as well."
The Lib Dems had 26 MPs at the end of the last parliament; they won 20 seats in 1992, but gained four more in by-elections and two from defectors from the Tory party, Emma Nicholson and Peter Thurnham.
Mr Ashdown yesterday made his final play for the votes of the Great Disillusioned in flying visits to eight constituencies and sending two million letters to floating voters.
After Tony Blair's reaffirmation of plans for a referendum on proportional representation, the Liberal Democrat leader sought to maximise his national percentage of the vote through the nationwide letter campaign.
He believes that substantial support in constituencies all over the country would be turned into a far greater number of MPs after electoral reform.
Mr Ashdown's letter went to undecided voters throughout Britain compiled from canvassing returns. In it, Mr Ashdown urges those who are concerned about the current "funding crisis" in education and health to turn their backs on Labour and the Tories.
The Liberal Democrat leader, who anticipated a Blair government at yesterday morning's press conference, said there was a "danger" that Labour would fail to deliver the necessary changes. He reminded floating voters that the Liberal Democrats had said what they wanted to achieve and how it would be paid for.
On the final day of his campaign - which has taken Mr Ashdown on a 17,300- mile odyssey around 64 constituencies - the Liberal Democrat leader flew by helicopter to eight key seats in southern England and the West Country.
In a refuelling stop at Exeter airport Mr Ashdown encountered Michael Heseltine. At first the Lib-Dem leader began to approach the Deputy Prime Minister, but then thought better of it with television crews and reporters in attendance. Such a conversation would have been "off message", as one of Mr Ashdown's aides put it.
After a long, hard campaign, Mr Ashdown seemed to be making speeches on auto pilot. At Haymoor Middle School, mid-Dorset, he told a throng made up largely of children which gathered around his helicopter that they would have to pay more taxes under a Liberal Democrat government.
To chants of "Paddy, Paddy!" he told them they wouldn't have to wait as long for a hip operation. The unthinking enthusiasm of 12-year-olds for a politician left a strange taste in the mouth.
Despite minor hiccups, Mr Ashdown has clearly enjoyed the hustings. He told reporters yesterday: "1992 was a good campaign. This has been a great campaign."
He felt his battle for votes had turned the corner on Monday night in Oxford when he was forced to address hundreds of his supporters who were unable to get into a packed town hall to hear his formal speech.
"I felt then that the party was getting stronger and stronger and the message we were putting across was getting a warmer and warmer welcome."
Last night, he told party activists to go and "work your socks off" in the final hours of the election campaign.Reuse content