Liberal Democrat leader Charles Kennedy has seen the launch of his party's election campaign boosted by the defection of a Labour candidate.
Charles Kennedy also launched a manifesto for urban Britain
Mr Kennedy said he was "delighted" to welcome former parliamentary candidate Stephen Wilkinson into the party.
The Lib Dem leader said he wanted to address people's hopes, not play on their fears, and make society fairer by increasing tax for the highest earners.
Both Labour and the Tories say the Lib Dems' plans are not properly costed.
Speaking before Mr Blair travelled to Buckingham Palace to ask the Queen for a dissolution of Parliament, Mr Kennedy pledged to be a positive force during the election campaign.
And unveiling plans to reinvigorate Britain's cities, he said "too often the spirit of urban community is undermined by crime and vandalism, by poverty and pollution".
Joined by former Ribble Valley candidate Mr Wilkinson, he spoke of the party's manifesto for urban Britain and emphasised plans to replace council tax - based on the value of houses - with a "fairer" system of local income tax, as well as 10,000 new police officers.
Mr Kennedy said: "Liberal Democrats want more police on the streets, more quality affordable housing, fairer local taxation, more sustainable green living, and want local people to have the power to determine their own priorities for their own communities."
Mr Wilkinson said he had become disillusioned with Tony Blair's "increasingly authoritarian" party.
Standing alongside the Lib Dem leader at Manchester Airport, he said: "I wholly oppose ID cards, I'm in support of local income tax as opposed to council tax.
"In general the issues the Liberal Democrats stand for are ones I am wholly in support of.
"I'm moving for very positive reasons. The things the Liberal Democrats believe in that I also believe in, that the Labour Party believed in when I joined, that is no longer the case."
"Who could have thought that a Labour government would become a lapdog to George Bush's right-wing Republican administration?"
He said he was angry at what he said was Labour's failure to "safeguard civil liberties" and accused the party of becoming "increasingly authoritarian"
He also criticised the use of the threat of terror to push for house arrest and compulsory ID cards and to justify the war in Iraq.
Mr Wilkinson, who said he had decided to leave some time ago, will not seek election as a Lib Dem member of Parliament but will campaign for them.
Mr Kennedy said: "When Labour cannot even retain the support of their own candidates, it is surely a sign of things to come."
Labour says it would keep the council tax, but reform it. Chancellor Gordon Brown also offered pensioners a one-off £200 council tax refund in his Budget.
They are also pledging to create 15,000 new affordable homes.
The Tories say they would offer households where all adults are over 65 years old a rebate covering up to half their council tax bill - up to a maximum of £500.
They also plan to boost police numbers by cutting red tape.
Mr Kennedy is visiting four other cities across Britain on Tuesday - Newcastle, Leeds, Edinburgh and Norwich.