There will be "an element of celebration" about the Liberal Democrat autumn conference next week, campaign chairman Lord Razzall has said.
Lib Dem leader Charles Kennedy saw the party gain 11 MPs
He said the party would go to Blackpool "in very good heart", having won 62 seats in the general election.
Research indicated that 50% of the electorate regarded themselves as "small L" liberals, Lord Razzall added.
The main task over the next four years would be to convert these into "big L" Liberal Democrat voters.
The party polled 23% in the last election, Lord Razzall said, adding that Labour was becoming "past its sell-by date" and the Conservative Party was incapable of winning.
"We are looking at the next general election with enormous confidence."
He added: "We maintain our belief that we are the real alternative to the Labour Government."
At the last election, the Liberal Democrats took 11 more seats than in 2001 but failed to oust several Tory front-benchers in target constituencies.
This was "disappointing", the then party president, Simon Hughes, admitted shortly after the results were known.
He partly blamed this on plans to replace council tax with a regionally variable local income tax.
Answering questions, Lord Razzall denied that the election campaign had been a "shambles" or that there had been a "kerfuffle" over Charles Kennedy's leadership.
He also found it "almost impossible to believe" the Lib Dems could do a deal with a Conservative Party led by any of the candidates announced so far.
The annual conference, for which delegates start gathering this weekend, will include a question and answer session with leader Charles Kennedy and debates on saving the Post Office and the Royal Mail.
School discipline, road pricing, the environment, anti-social behaviour and civil liberties will also be discussed.
The conference will end with a speech by Mr Kennedy on Thursday morning.