US President Barack Obama has taken the lead over Republican rival Mitt Romney in the three biggest swing states of the 2012 election, according to a new poll released Wednesday.
The latest Quinnipiac University Swing State Poll puts the president in significantly better standing than the same survey seven weeks ago, when Obama was ahead in Pennsylvania but Florida and Ohio were too close to call.
The three are by far the largest of the roughly 10 states in the November election that are seen as up for grabs by either candidate, and many experts consider them to be the critical battlegrounds to watch in 2012.
Quinnipiac has Obama ahead of Romney by 45-41 percent in Florida; 47-38 in Ohio; and 45-39 in Pennsylvania.
"If he can keep those leads in all three of these key swing states through election day he would be virtually assured of re-election," said Peter Brown, assistant director of the Quinnipiac University Polling Institute.
Since 1960, no candidate has won the White House without taking at least two of the three states. Obama swept the trio in 2008.
Brown was quick to stress that the election was still more than four months away, "which is a lifetime in politics."
But the data suggests voters in the three states like Obama better. He has a net favourable view among Ohio voters, and his favourability rating is about even in the other two states.
Romney's favourability rating is negative in all three, Quinnipiac said.
In particular, voters approve of Obama's recent presidential action halting deportations of some younger illegal immigrants, according to the survey.
And the president's approval figures on the economy have improved slightly, drawing him virtually even on that front with Romney, a multimillionaire former venture capitalist who has touted his business acumen.
"For much of the last year, more voters in these swing states have said Romney would do a better job on the economy," Brown said.
"That advantage has largely disappeared, at least for now."
The poll's figures are somewhat more favourable to Obama than other recent surveys.
Obama tops Romney by 2.6 percentage points in an average of national polls compiled by the RealClearPolitics website.
The same website has Obama edging Romney by 1.8 points on average in Florida polls and barely ahead by 1.0 point in Ohio, but comfortably up by 8.0 points in Pennsylvania.
Quinnipiac said Obama's overall margin is built on his big lead among women, younger voters and African-Americans. It found "no measurable black support for Romney" in Ohio, and just single digits in Florida and Pennsylvania.
Hispanics are also seen as a key demographic, and Obama holds a substantial 56-32 point lead among Florida's large Hispanic population.
The poll, conducted by telephone June 19-25, surveyed 1,200 or more voters in each of the three states, and has a margin of error of plus or minus 2.8 percent.