The US presidential rivals have begun campaigning in earnest, as a new opinion poll put Republican John McCain ahead of Democrat Barack Obama.
Fresh from being nominated at their party conventions, the two men are now gearing up for the 4 November poll.
A USA Today-Gallup poll put Mr McCain ahead for the first time in months.
Candidates often see a bounce in the polls after the conventions but Mr McCain's choice of Sarah Palin as running mate is being seen as key.
Mr McCain has tried to strike a balance between distancing himself from an unpopular presidency and rallying the party's conservative base.
Mrs Palin wowed the Republican convention crowd with her speech, helping to re-energise his campaign.
Mr McCain said that "the electricity has been incredible" at rallies ever since he invited the Alaskan governor to join his ticket.
"She has excited people all over the country. I would love to say it was all because of the charisma of John McCain, but it is not," he told CBS on Sunday.
The USA Today-Gallup poll, which was released on Sunday, showed Mr McCain leading Mr Obama by four percentage points, 50 to 46.
A USA Today poll taken before the Republican convention showed Mr McCain trailing Mr Obama by seven points.
The latest poll had a margin of error of plus or minus three percentage points.
The results of a Reuters/Zogby poll, also released over the weekend, gave Mr McCain the edge, with 50 percentage points to 46.
The Rasmussen Reports daily Presidential Tracking Poll showed John McCain with a one-point lead.
Mr McCain and Mrs Palin are scheduled to be in Missouri on Monday.
Mr Obama is campaigning in the crucial swing state of Michigan. His vice-president, Joe Biden, was appearing in Wisconsin and Iowa, while Hillary Clinton is on the campaign trail in Florida.
Despite the frenetic pace of the presidential race, the candidates will stop campaigning on Thursday to appear together in New York on the anniversary of the 11 September 2001 attacks.
They said they would put aside politics to honour the memory of the nearly 3,000 people who died.