Michael Howard launched the Conservative election campaign yesterday by criticising the "smirking politics" of the prime minister.

The Tory leader said voters "can either reward Mr Blair for eight years of broken promises and vote for another five years of talk.

"Or they can vote Conservative, to support a party that's taken a stand and is committed to action on the issues that matter to hard-working Britons."

Howard, who was boosted by opinion polls earlier in the day, then flew by helicopter to regional launches in Birmingham and Manchester.

Today Howard will make a speech in Leeds on how to counter "yob culture".

Charles Kennedy, the Liberal Democrat leader, told supporters the election was "much more fluid" than ever before.

Speaking during a nationwide tour, Kennedy said his party was determined to shun the "negative campaigning" of his rivals.

Lord Rennard, the party's chief strategist, also pledged that "we will be the most travelled campaign and Charles will meet the most people and be the most visible and accessible."

The Lib Dems will also publish their manifesto on family policies today.

Writing in the Financial Times, Stephen Byers, the former Labour cabinet minister, warns against the two main parties pursuing negative campaigning.

"A Punch and Judy election campaign simply will not be tolerated by an electorate whose patience of such conduct is coming to an end," he says.