WASHINGTON (AFP) - For the first time, White House hopeful Barack Obama leads his Republican rival John McCain in three of the biggest battlegrounds of November's election, according to a new poll Wednesday. The surveys by Quinnipiac University also found independent voters are opposed to defeated primary contender Hillary Clinton running as Obama's running mate on the Democratic ticket. Another poll out Wednesday by Zogby had Obama leading McCain by 47pc to 42 nationally, with a 22-point lead among all-important independents. The Quinnipiac polls had Obama besting McCain 52-40pc in Pennsylvania, 48-42pc in Ohio, and 47-43 in Florida. All three states are crucial building blocks to an election triumph for either candidate in November. In all three states, Obama leads McCain among female voters by 10 to 23 percentage points, but among men the two contenders are "too close to call", Quinnipiac University Polling Institute assistant director Peter Brown said. The Quinnipiac surveys found that while most Democrats back Hillary to join Obama's ticket, clear pluralities of independent voters in all three states were against seeing the former first lady run as his vice president. The Quinnipiac polls also suggested that one in five voters see McCain's age as a reason to vote against him. At 72 in January, the Republican would be the oldest president sworn in to a first term.