Charles Kennedy says the Liberal Democrat campaign mood is the best since the "heady days of 1983".
Charles Kennedy says the Lib Dems are the "winning team"
The Lib Dem leader made the claim as he unveiled his party's plans to retrain teachers and reduce class sizes.
Mr Kennedy says the Tory campaign accusing Tony Blair of lying over the Iraq war shows Michael Howard has accepted he is "losing this election".
Labour say voting Lib Dem could let in Mr Howard. The Tories say Lib Dems will raise taxes and be soft on crime.
The election campaign took an increasingly personalised tack on Tuesday as the Conservatives prepared to unveil their latest poster, which targets Mr Blair.
It says: "If he's prepared to lie to take us to war, he's prepared to lie to win an election."
Labour has hit back with posters claiming Mr Howard has a "hidden agenda" for the NHS.
Mr Kennedy said he did not think the Conservatives' personal attacks on Mr Blair would do the party any good.
"I think what the latest gambit from the Conservatives shows is that they have concluded internally, as indeed Michael Howard has all but acknowledged publicly, that they are going to lose this election - so they are falling back now on the most negative form of personalised campaigning," he said.
"It won't do them any good: it won't do the quality of the general election debate any good."
Mr Kennedy added: "I think they are the losing team in this election while we are looking increasingly the team which is winning."
Asked if he believed the prime minister was a liar, Mr Kennedy replied: "I've not used that particular four-letter word - I'm not persuaded it's guaranteed to be true."
Instead, Mr Kennedy highlighted the mood of a Liberal Democrat rally in Cambridge on Tuesday, following the defection to the party of former Labour MP Brian Sedgemore.
He said the meeting "had a revivalist feel to it of the type that I have not experienced since the run-up to the 1983 general election, those heady days".
"If that is a barometer as to what is going on in parts of this country, I think we are in for a very exciting indeed final days of the campaign."
He said Mr Sedgemore's defection was typical of "potentially millions" of former Labour voters who could switch to the Liberal Democrats, and argued that the campaign involved "genuine three-party politics".
"Depending what constituency and what region you go to in what part of the country, you have got very different findings to the benefit of all three parties," he said.
Educating the 'specialists'
Turning their attention to education, the Liberal Democrats pledged to introduce 21,000 new teachers to reduce class sizes for primary schools.
The party would spend £230m over the course of the next Parliament to ensure that in six core subjects, every secondary school pupil was taught by a properly qualified specialist teacher in those subjects.
Mr Kennedy said there were currently 40,000 teachers who were not specialists in their core subjects.
"Students deserve better than being taught by a teacher who is just one page ahead in the text book because there is a shortage of specialist teachers in our secondary schools," said Mr Kennedy.
"Our guarantee is that in the core subjects - maths, English, science, modern languages and information and communication technology - all pupils will be taught by a properly qualified teacher who is expert in that subject,."
The education polices would be paid for from the £5bn of existing government spending that the Lib Dems would spend elsewhere.