HARRISBURG — A wave of independent voters who are disenchanted with President Barack Obama are giving Republican Pat Toomey an apparent edge over Democrat Joe Sestak in Pennsylvania's closely contested race for U.S. Senate, a new poll showed Wednesday.

The poll by Quinnipiac University shows Toomey with 50 percent — an important number for a candidate to reach — to Sestak's 43 percent among likely voters.

"When a candidate's at 50 (percent) or over, that means the candidate just has to hold his or her own the rest of the way to have a majority," said Peter Brown, assistant director of Quinnipiac University's Polling Institute. "And so that's symbolically important and it's also strategically important."

Independent voters are breaking heavily for Toomey, 54 percent to 36 percent. Many are also unhappy with Obama, with 53 percent to 38 percent saying they want Pennsylvania's new senator to oppose his policies and 59 percent to 37 percent saying they disapprove of his job performance.

Brown said it is likely that independents are more conservative than they were in 2006 and 2008 when they supported Democrats, including Obama. That's because some unhappy Republicans became independents, while some independents switched their registration to the Democratic Party, he said.

With control of the U.S. Senate potentially at stake, national party committees and interest groups such as the U.S. Chamber of Commerce have already made Pennsylvania's Senate seat a priority, pouring millions of dollars in TV ads into the state.