Gordon Brown and Tony Blair returned to domestic politics yesterday, as the party prepared for a difficult annual conference.
Mr Blair, back from holiday in Barbados, held a summit on "social exclusion", to be followed by a regional tour next week.
The Chancellor, speaking for the first time since the birth of his second son, James, pledged to avoid "unfunded tax cuts".
It followed a jittery few weeks, when confusion over party leadership has been acute.
Former Cabinet Minister Stephen Byers, a close ally of the Prime Minister, infuriated the Chancellor's supporters by calling for the abolition of inheritance tax.
His comments were seen as a dig at Mr Brown's ability to lead Labour to election victory.
The Chancellor has a reputation for being more left wing than Mr Blair, and his party enemies claim he would scare middle class voters on taxation.
Europe minister Geoff Hoon said voters were starting to see Conservative leader David Cameron as a serious alternative to Tony Blair.
Culture Secretary Tessa Jowell warned the Prime Minister's plans to step down as leader were creating "uncertainty".
And Lord Chancellor, Lord Falconer, said Mr Blair was the right person to lead the party.
Mr Brown's comments were seen as a rejection of the tax proposal.
He said: "No political party will be trusted if it promises stability in one breath and unfunded tax cuts in the next.
"To make unfunded promises, play fast and loose with stability, indeed to play politics with stability, is a return to bad old days - something I will never do and the British people will not accept."
One of his closest allies, Treasury Minister Ed Balls, publicly warned Labour MPs they risked plunging the party into chaos if they tried to block Mr Brown's ascent.
Mr Balls said: "I think people remember what happened to the Tories in the late 1980s and the early 1990s where their transition descended into division.
Both Blairites and Brown-ites agreed it would be "unforgivable" to let "factionalism" take over, he said.
"There are a few mavericks, but put them to one side. The vast majority want a united transition, an orderly one which focuses on long-term policy and makes sure we can build trust with the public and show we are the governing party for today."
Meanwhile, the Prime Minister attempted to focus on policy issues.
He spent the day in his country residence, Chequers, where he led a summit on "social exclusion" with Ministers and experts, ahead of a speech and regional tour next week.
Downing Street said Mr Blair would spend the week engaged in "policy preparation" - looking particularly at areas such as NHS waiting targets, the academy schools programme, globalisation and the Middle East.
The aim is to focus attention on policies rather than Mr Blair's future.
But Labour's annual conference, in Manchester next September, will be dominated by debate about how Labour can "renew" itself - code at Westminster for the Prime Minister resigning.