Presidential campaign TV ads are off the air in Pennsylvania and the presidential candidates are scarce. That leaves surrogates to stand in.

On Wednesday, Gov. Tom Corbett held a news conference in Philadelphia to stump for the Republican presidential nominee, Mitt Romney. That's a day after U.S. Sen. Kelly Ayotte of New Hampshire visited Pennsylvania for Romney. On Thursday and Friday, Romney's son, Josh, is attending events in western Pennsylvania.

Last Sunday, Jill Biden, the wife of vice president Joe Biden, headlined a campaign event in Pittsburgh with Democratic National Chair Debbie Wasserman Schultz. Biden himself last visited to commemorate the anniversary of the Sept. 11 attacks.

President Barack Obama last visited in June. Romney last visited in July and is scheduled to attend a private fundraiser in Philadelphia on Sept. 28.