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 reelection,” 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 favorable view among Ohio voters, and his favorability rating is about even in the other two states. Romney’s favorability rating is negative in all three, Quinnipiac said.