Romney and supporters hope his message of austerity, lower taxes and less regulation -- combined with criticism of Obama's economic record -- will win over New Hampshire voters, The New York Times reported.
Privately, the Times said, Romney aides view New Hampshire as potentially critical in a close national election.
Polls show Obama has a lead but the president has had a head start, with a campaign that has been operating in the state for months, while Romney's state director just started in May.
"We Republicans are still putting the pieces together after the primary campaign, and not even running on all cylinders yet," said Michael P. Dennehy, a veteran Republican operative. "I think it's going to be a very close race -- two, three, four points, maximum."
Romney appeared Friday at an abandoned 19th-century bridge repaired with $150,000 in federal stimulus money.
"This is the absolute Bridge to Nowhere if ever [there] was one," Mr. Romney said. "That's your stimulus dollars at work."
Supporters of the project noted there had been bipartisan support for the effort, including local Republicans supporting Romney, to preserve the landmark bridge as a part of local history.
At an April event in Exeter, Biden spoke of tax fairness.
Meanwhile, The Hill reported, Romney and his wife, Ann, have given $75,000 each to the joint Romney-Republican National Committee Victory Fund for the month of May.
That's the maximum amount they could legally give the committee.