George Galloway has said next month's local elections will be a referendum on New Labour, claiming they could be "the last nail in Tony Blair's coffin".
Mr Galloway: Fierce critic of Iraq war
The Respect MP for Bethnal Green and Bow said Labour supporters wanted Tony Blair to go and would use their votes in the hope of unseating him.
Respect was focusing its efforts in East London running candidates in every ward in Newham and Tower Hamlets.
But nationwide they were targeting their efforts at specific wards.
"This will be the last blow that will knock out Tony Blair," the MP claimed.
"It won't knock him out the next day but it will knock him out this year, rather than in 2009."
Other parties launch
Mr Galloway, who nearly missed the launch after being stuck in traffic, said it made sense for Respect to build on its successes in East London where he described them as "fighting for power".
The outspoken anti-war MP, who was expelled from the Labour Party and who recently hit the headlines in the Celebrity Big Brother reality TV programme, said the biggest issue there was housing but said people still raised the Iraq war.
"When George Bush said 'mission accomplished' tens of thousands of people were alive who are now dead," he said at the event in central London.
Respect was being well received on the doorstep, he added.
Labour, the Liberal Democrats and the UK Independence Party have all launched their campaigns for the 4 May local elections.
The Greens are to launch on Tuesday. The Conservatives are expected to officially launch their campaign the following week.
Mr Galloway had faced criticism for his decision to appear on Celebrity Big Brother at a time when he had other duties as an MP.
At the time minister for London Jim Fitzpatrick said: "I am not too surprised about it, as Mr Galloway is a C-list politician with an A-list ego."