Tony Blair promised Gordon Brown his job is safe if Labour win a third term, as he focused on Labour's economic record.
The Prime Minister and Chancellor appeared together at Labour's first press conference of the campaign, in a bid to squash reports of splits in the Government.
It has been rumoured that Mr Blair intends to sack Mr Brown after the next election.
The Conservatives focused on law and order, warning that "yob" tenants could lose their driving licenses, or face eviction from council homes and be forced into bed and breakfast accommodation.
And the Liberal Democrats launched a "mini-manifesto" for families, promising mothers a minimum £170 a week maternity pay for six months.
The proposal would cost £700 million and would be funded out of Whitehall efficiency savings, the Lib Dems said. Charles Kennedy, the Liberal Democrat leader, will be in Birmingham today to launch the party's West Midlands campaign.
The Lib Dems are hoping to make a breakthrough in the city on May 5 by taking their first Birmingham seat.
They are targeting Yardley, held by Labour, as well as Solihull and West Worcestershire, held by the Tories.
But the party could also face a battle to hold on to Hereford and Ludlow, the only seats they won in the West Midlands in 2001.
A Lib Dem official said: "Charles will say that we are challenging both Labour and the Conservatives in the West Midlands." Labour is to promote its policies on crime and antisocial behaviour in Birmingham today and the Conservatives are sending party chairman Liam Fox to the city.
Suggestions that Mr Brown could be sacked, or moved to the Foreign Office, were seen as a sign that the Prime Minister has finally had enough of the feuding.
But yesterday Mr Blair said: "This is probably the most successful Chancellor the country has had for 100 years.
"He has delivered economic stability, and low interest rates, and low unemployment, and better living standards.
"So without breaching any protocols about how I decide things, we would be pretty foolish to put that at risk."