Peter Mandelson said he would "make a contribution" to Labour's next general election campaign, but has not been brought back to mastermind it.
The new Business Secretary, who returned to the Cabinet in a shock move on Friday, also revealed he had spoken to Tony Blair before agreeing to take the role.
And he insisted that any past disputes with Gordon Brown were behind him, saying they were both part of the "Labour family".
Speaking on Sky News, Mr Mandelson said the Government's main priority would be tackling the tough economic circumstances facing the country.
Comparing the economy to an ill patient, he said the overall task would be to nurse it back to health.
But when the time came to go to the polls, Mr Mandelson said, he would try to show the country what Labour had to offer.
"If I can play my part in that - along with other party members - and make a contribution, that's what I want to do and that's what I will do," he said.
But asked whether he had been brought back to run an election campaign, Mr Mandelson said: "No I'm not. I think you'll find that somebody else is going to be affirmed in that role, somebody I know and trust and admire.
"Look, we are all part of the same team now and that's what the party wants, it's what the country needs, so when it comes to the point that we have to shift our focus from what we are absolutely going to concentrate on in the mean time, which is the economic crisis facing the country, and in due course we come to fighting an election, yes I will be there supporting the Labour team."
Mr Brown is expected to complete his most significant reshuffle since becoming Prime Minister with the high-profile post of immigration minister going to Phil Woolas - who sparked controversy after saying that Muslim women wearing the veil could spark "fear and resentment" among non-Muslims and warning that the practice of first-cousin marriage in Britain's Pakistani community was leading to high numbers of birth defects.
