Former US President Bill Clinton will join White House hopeful John Kerry to campaign in Pennsylvania, aides say.
More campaign events are likely to be scheduled for Bill Clinton
The 58-year-old will appear at a rally on Monday, seven weeks after he had quadruple heart bypass surgery.
Mr Clinton, renowned as a passionate and able campaigner, has also recorded phone messages for the Kerry campaign while recuperating at home in New York.
Correspondents say his heart problems curtailed what had been expected to be a prominent role in the Kerry bid.
Joe Lockhart, a senior adviser to Mr Kerry and former press secretary to Mr Clinton, said the two-term president also hoped to campaign separately for Mr Kerry.
Observers say Democrats will be hoping that Monday's appearance in Philadelphia will help Mr Kerry's chances in Pennsylvania, one of the battleground states that could be won by either candidate and which may decide the outcome of the election.
Mr Clinton also sent out an e-mail fundraising appeal to Mr Kerry's supporters, saying "nothing less than the future of our country is at stake".
"America's future is on the ballot this year. Let's use these final days of the campaign to win the victory that is within our grasp, and secure the kind of future we want for our children. I'm counting on you," he wrote.