Republican challenger Mitt Romney has tried to drive a wedge between Barack Obama and former president Bill Clinton, who has taken an increasingly prominent role in the re-election effort.
A new Romney campaign ad tries to cast Mr Obama as a big-government liberal, accusing him of dismantling the groundbreaking welfare reforms Mr Clinton put in place.
The Democrats recently announced that Mr Clinton would have a prime speaking role at the party's national convention in September, which will serve as a formal push into the final weeks of campaigning for the November election.
With the race tight and Mr Romney and the Republicans leading in fundraising for a third straight month, the Democrats are seeking to take advantage of Mr Clinton's popularity and strong economic record while in office.
But the new ad criticises Mr Obama for removing work requirements from federal welfare regulations, a key element of Mr Clinton's 1996 welfare reforms. The ad contends that Mr Obama simply wants to hand out welfare checks, while Mr Romney would restore the work requirement.
"His policies will take America backward - back to the discredited liberalism of a bygone era where bigger government programs and bigger government checks were the answer to every problem, and accountability was not on the agenda," Lanhee Chen, Mr Romney's policy director, said.
The Democrats responded by renewing efforts to paint Mr Romney as a profit-driven businessman.
The White House responded that Mr Obama's decision last month to change welfare requirements gives states the flexibility they have been asking for to make the programme more efficient. Mr Romney, a former Massachusetts governor, was among several Republican governors who signed a letter in 2005 asking for more "waiver authority."
This year's election hinges on which candidate voters decide is best to deal with the struggling US economy and high unemployment. Polls show Mr Obama and Mr Romney in a virtual tie.
Mr Clinton is also helping the Democratic-leaning independent group Priorities USA Action boost its sluggish fundraising. The former president will host an event in New York next week to help it raise money.