May 1 (Bloomberg) -- Hillary Clinton runs stronger than Democratic presidential rival Barack Obama in a match-up against Republican John McCain in the crucial swing states of Pennsylvania, Ohio and Florida, a Quinnipiac University poll shows.

Clinton's support in the three states is built on white working-class voters, who also were essential to her primary victories over Obama in Ohio and Pennsylvania, the poll found.

Clinton, a New York senator, would get 49 percent to McCain's 41 percent among all voters in Florida and she is ahead of McCain 48 percent to 38 percent in Ohio. In Pennsylvania, Clinton bests McCain 51 percent to 37 percent in a head-to-head match-up.

By contrast, Obama, an Illinois senator, is statistically even with McCain in Florida and Ohio, while leading him in Pennsylvania by 47 percent to 38 percent, according to data released by the university's polling institute.

Clinton and McCain are tied among white voters in Florida and she gets a plurality of their support in the other two states. Obama, the first black candidate with a serious chance of winning the presidency, trails McCain among whites in all three states.

``There's no indication that Obama's problems with white, working-class Democrats in the Ohio and Pennsylvania primaries have gone away,'' Peter Brown, assistant director of Quinnipiac's polling institute in Hamden, Connecticut, said in a statement.

Bush Ties Hurt McCain

McCain, an Arizona senator, is hurt in the three states because he is linked to President George W. Bush, Brown said. McCain's age -- he would be 72 on Inauguration Day -- also is a concern for voters, according to the poll.

The economy was mentioned most often by voters as the top issue in the election, followed by the war in Iraq.

Florida, Ohio and Pennsylvania account for 68 of the 270 Electoral College votes needed to win the presidency. No one has won the presidency since 1960 without winning at least two of the three states.

The Quinnipiac poll was conducted April 23-29 and the margin of error was plus or minus 2.6 percentage points in Florida, 2.9 points in Ohio and 2.5 percentage points in Pennsylvania.

To contact the reporter on this story: Joe Sobczyk in Washington at jsobczyk@bloomberg.net.

Last Updated: May 1, 2008 09:00 EDT