Republican presidential candidate John McCain got a bounce in opinion polls from his convention and now runs even or slightly ahead of Democratic rival Barack Obama with eight weeks to go in the White House race.
Mr McCain's surprise choice of conservative Alaska Governor Sarah Palin as his running mate also sparked a burst of grass-roots Republican enthusiasm, polls showed, an encouraging sign for party strategists worried about turnout in the November 4th election.
Republicans have battled an unfavorable political environment all year amid a faltering economy and Republican President George W. Bush's unpopularity, but party officials around the country have reported a jump in volunteers and donations.
"The change in enthusiasm is huge, that's what wins these things," Republican consultant Rich Galen said. "Given the political atmosphere, Mr Obama did not want to be coming out of these conventions tied - he needed to come out with a lead."
Three polls taken since the Republican convention ended on Thursday show Mr McCain with a lead of 1 to 4 percentage points - within the margin of error - and two others show the race dead even.
Another poll released yesterday, by the Washington Post/ABC News, gave Obama a 1-point edge among registered voters and McCain a 2-point edge among likely voters - both within the margin of error.
Heading into the conventions - Mr Obama and Democrats met the week before Mr McCain and the Republicans - the two candidates had been running even or Obama held a small lead in most polls.
Conventions typically give a candidate a short-term bounce, but this year's back-to-back gatherings appeared to cut short the benefit for Mr Obama and gave Mr McCain a slightly bigger boost. Democrats said the new round of polls was not a cause for alarm.
"Obama had the ball and scored at his convention, then McCain got the ball and scored. So we're back to where we started - dead even," said Democratic consultant Dane Strother.
"This race is going to come down to some obscure county in Ohio or Florida, just like we knew it would," he said.
State-by-state polls show Mr Obama with a lead in more states than Mr McCain, although about 10 remain toss-ups and neither candidate has a clear edge in accumulating the 270 electoral votes needed to claim the White House.
As in 2000 and 2004, the candidate who wins two out of three of the big states of Ohio, Florida and Pennsylvania could be the ultimate winner. Mr Obama has held a slight lead in Pennsylvania polls, while Florida and Ohio are toss-ups where turnout could be the deciding factor.
A USA Today/Gallup poll published yesterday showed the number of Republicans who said they were more enthusiastic than usual about voting was around 40 per cent in August, compared to about 60 per cent for Democrats.
Since the pick of Ms Palin, a staunch anti-abortion and pro-gun conservative, the number of Republicans who are more enthusiastic about voting jumped to 60 per cent, with Democrats at 67 per cent.
In her speech at the convention, Ms Palin mocked Obama as an elitist who was out of touch with the struggles of American families, raising the sort of cultural issues that worked for Mr Bush in the last two presidential elections.
"She has created a culture discussion again, and that's what Republicans are so good at winning," Mr Strother said.
The choice also revved up Mr McCain, allowing him to try to reclaim the reform label he had largely abandoned as he courted conservatives during the Republican presidential nomination battle.
"We've been under siege with this idea that John McCain is running for George Bush's third term. We've successfully reminded people 'No, this is who he is.' And it's had a positive effect," Mark Salter, a senior McCain adviser, told reporters.
With the conventions completed, the last major items on the campaign calendar are the three presidential debates, with the first on September 26th. A vice presidential debate is scheduled for October 2nd.