HARRISBURG, Pa. (AP) — The TV screens of Pennsylvanians are suddenly empty of presidential campaign advertising as the post-Labor Day campaign season begins.

Pennsylvania, which traditionally has been treated as an important swing state in presidential elections, has thus far seen a couple dozen different TV ads during the last five months that cost millions of dollars.

But independent polls over the summer have consistently shown President Barack Obama, a Democrat, with a lead over his Republican challenger, former Massachusetts Gov. Mitt Romney.

Republicans maintain their nominee still can win Pennsylvania, which has sided with Democrats in the last five presidential elections.

"Our internal polling shows that Romney is still very competitive in the commonwealth of Pennsylvania," Bob Asher, a top Romney campaign fundraiser in Pennsylvania, said Wednesday.

One problem for a statewide campaign is that Pennsylvania has at least a half dozen media markets and it is costlier to advertise here than many other swing states, campaign professionals say.

Another problem is that the heavily populated and expensive Philadelphia media market includes portions of New Jersey and Delaware — two states that are considered out of reach for Romney.

For the time being, ads are primarily targeting a handful of closely watched states: Colorado, Florida, Iowa, Nevada, New Hampshire, North Carolina, Ohio, Virginia and Wisconsin.

Jonathan Collegio, a spokesman for Crossroads GPS, a group associated with Republican strategist Karl Rove, said the group may return to advertising on TV in Pennsylvania in the future.

"For our current buy, Pennsylvania is not part of our strategy. That could change as the dynamics change," Collegio said.

Romney's campaign last advertised on TV in Pennsylvania in the first half of April, when Romney was still competing for the GOP's nomination with former Pennsylvania Sen. Rick Santorum. A Romney campaign spokeswoman on Wednesday would not discuss the campaign's TV advertising plans or strategy.

Since then, the Obama campaign and a pro-Obama super PAC, Priorities USA Action, have aired ads in Pennsylvania, as have Crossroads and two other pro-Romney groups, Americans for Prosperity and Restore Our Future.

Valerie Caras, a spokeswoman for the state Republican Party, said TV advertising is only part of the campaign operation, while the Romney campaign and the national GOP are investing heavily in a joint campaign operation that includes 20 field offices.

"When you look at the campaign from the big picture sense, the ad spending is certainly important, but everything else we've been doing ... really shows that both the national campaigns believe we can win Pennsylvania," Caras said.

Currently, Democrats in Pennsylvania outnumber Republicans by almost 1.1 million registered voters. That compares with a more than 1.2 million voter advantage Democrats held when Obama won Pennsylvania in 2008 by 10 percentage points, or about 620,000 votes, over Republican John McCain.


Associated Press writer Beth Fouhy in Charlotte, N.C., contributed to this report.