The US presidential race had seemed on the verge of slipping from Republican Mitt Romney's grasp a week ago, but now he has erased President Barack Obama's once-substantial lead in polls and made the race for the White House highly competitive once more.
In a clear shift four weeks before Election Day on November 6, a new round of opinion polls showed essentially a dead heat after a strong debate performance by Romney last week.
A Reuters/Ipsos daily tracking poll on Tuesday found Obama and Romney tied among likely voters at 45 per cent each, ending a month during which Obama led the survey.
|In-depth coverage of the US presidential election
Other polls also reflected the Romney surge. He led by two percentage points in Gallup's daily tracking poll and four points in a Pew Research Center poll.
Strategists say Obama still holds an advantage in the handful of contested states that will decide the election, but
there were signs that Romney may be able to expand the battlefield to states that had been considered beyond his reach.
Pennsylvania and Michigan - regarded until this week to be sure bets for Obama - suddenly do not look so safe for him
as several polls showed his lead in both states shrinking to three percentage points.
A victory in either of those states would multiply Romney's possible pathways to victory and reduce his need to carry
make-or-break states such as Virginia or Florida.
"Everyone in America is really watching the state-wide polls, what's happening in what we call 'FlOhVa' - Florida, Ohio and Virginia," said former Congressional campaign manager Jason Johnson.
"If those states begin to change and begin to shift toward Mitt Romney, then we're seeing a fundamental change in the race, but right now, most polls show Barack Obama retains a lead in Ohio, retains a lead in Virginia, he retains a slight lead in Florida - and those are the three states that this whole election is going to come down to."
|Former Congressional campaigner Jason Johnson
on distinctions between recent polls
Inevitably close race
Both campaigns downplayed the significance of the polls and said they have always believed the race would be close.
"You can't put too much stock in this idea of momentum. I think it's an elusive thing," Romney aide Kevin Madden told
reporters aboard the campaign plane.
"We've always felt this race would be close," Obama spokeswoman Jen Psaki told reporters as they flew from California to Ohio, where the president spoke on Tuesday, encouraging college students to vote early.
Tuesday was the last day to register to vote in the state of Ohio, and early voting began last week.
"A lot of Democratic counties have seen a huge increase in early voting, which is a key part of Obama's strategy," said Johnson. "Early voting is up by 30 per cent this year over 2008, and that sort of suggests that Barack Obama might already have some money in the bank, even before the actual November election day."
Pollsters also said the latest results more accurately reflected the underlying dynamic of a closely divided electorate
and a lacklustre economy.
Obama's earlier wide lead likely would have narrowed regardless of last week's debate, which put Romney in the lead.
Bill Schneider, a political analyst with the Third Way political research centre, told Al Jazeera that winning debates will not necessarily mean Romney will win.
"In 2004, John Kerry was judged to have every debate against President George W Bush," said Schneider, of the heated race that saw the Democratic senator from Massachusetts challenging the incumbent Republican president.
"But Bush won the election.Your prize for winning a debate is just that people think you're a better debater."
Schneider added that the debate was effective in giving Romney a boost as it was cast as "a referendum on Obama".