Prime Minister Gordon Brown has left 10 Downing Street to meet with Queen Elizabeth II at Buckingham Palace to ask her to dissolve Parliament so a national election can be held May 6.

The symbolic act marks the start of the general election campaign as Brown fights for his political future with the Labour Party trailing in opinion polls after 13 years in power.

Brown plans to publicly announce the election date after meeting with the queen. He says his success at managing the economic recession means he should be returned to power.

Opposition Conservative Party leader David Cameron has also launched his campaign with an ambitious three-city tour.