Democratic presidential nominee Barack Obama leads Republican rival John McCain among likely voters in Ohio and Pennsylvania while in Florida the race is too close to call, new Quinnipiac University polls found.

Obama, an Illinois senator, received 50 percent support in Ohio compared with 43 percent for Arizona Senator McCain. In Pennsylvania, Obama is ahead 52-42 percent. The candidates are in a statistical tie in Florida, where Obama is backed by 47 percent of likely voters compared with McCain's 45 percent, unchanged from a similar Oct. 29 survey.

No president has taken office since 1960 without winning at least two of those three swing states, according to Hamden, Connecticut-based Quinnipiac. The polls were conducted separately in each state from Oct. 27-Nov. 2.

A majority of likely voters in Ohio, Pennsylvania and Florida say the economy is the most important issue. In each state, Obama, 47, is seen as the more effective candidate than McCain, 72, to work with Congress on the financial crisis.

"Voters overwhelmingly say the economy is the major issue that leads to their vote and they see Senator Obama as better able to handle the nation's money problems," Peter Brown, assistant director of the Quinnipiac University Polling Institute, said in a statement.

In Ohio, a separate survey sponsored by the University of Cincinnati has Obama leading McCain 51.5-45.7 percent among probable voters. The poll of 1,308 probable voters from Oct. 29- Nov. 2 had a margin of error of plus or minus 2.7 percentage points.

The Quinnipiac poll of 1,773 likely voters in Florida had a margin of error of plus or minus 2.3 percentage points. There were 1,574 likely voters surveyed in Ohio and 1,493 in Pennsylvania. Both Ohio and Pennsylvania polls had a margin of error of plus or minus 2.5 percentage points.