Here are some of the top campaign stories on the AP wire today.

Romney says he's paid at least 13 percent in taxes every year

GREER, S.C. (AP) -- Mitt Romney says he's never paid less than 13 percent of his income in taxes during the past decade.

Romney told reporters Thursday in South Carolina that Democratic Senate Majority Leader Harry Reid's claim that Romney paid no taxes in some years is, quote, "totally false."

Reid had claimed it was possible Romney was refusing to release more than two years of returns was because Romney didn't want to reveal that he had paid no taxes.

Romney said: "Every year I've paid at least 13 percent."

He says he's also given generously to charity and that, including those contributions, he's given up more than 20 percent of his income each year.

Romney has released his 2010 tax return and says he'll release his 2011 return before the Nov. 6 election.

UPDATE: Obama campaign says Romney has to prove what he paid

GREER, S.C. (AP) -- An Obama campaign spokesman is calling on Mitt Romney to "prove it."

She's reacting to Romney's statement today that he has never paid less than 13 percent of his income in taxes during the past decade. Romney is still declining to release his returns from before 2010.

Romney told reporters today in South Carolina that Democratic Senate Majority Leader Harry Reid's claim that Romney paid no taxes in some years is, quote, "totally false." Reid had claimed it was possible Romney was refusing to release more than two years of returns was because Romney didn't want to reveal that he had paid no taxes.

Romney said: "Every year I've paid at least 13 percent."

He says he's also given generously to charity and that, including those contributions, he's given up more than 20 percent of his income each year.

Obama gives campaign pep talk to Dem staffers

WASHINGTON (AP) -- President Barack Obama is visiting Democratic Party headquarters to thank staffers for their work and rev them up for the fall campaign.

A spokesman for the party says Obama appreciates the staff's hard work and that he made Thursday's trip to "fire them up for the months ahead." Reporters were not allowed into the building with Obama.

The president returned to Washington late Wednesday after five days on the road.

He spent the weekend at home in Chicago, where he spent time with friends and held several fundraisers for his campaign. He then took a three-day bus trip through Iowa, a key Midwestern battleground state.

Ryan on Medicare cut: Obama did it first

WARREN, Ohio (AP) -- Republican vice presidential contender Paul Ryan says he never would have included a $700 billion Medicare cut in his budget if President Barack Obama hadn't done it first.

Mitt Romney and his running mate Ryan have been criticizing Obama in recent days for taking Medicare funds to help pay for his health care overhaul. But the Republican candidates haven't mentioned that Ryan's own budget proposal included the same cut.

A reporter pressed Ryan on the issue during an impromptu stop at a local hot dog restaurant on Thursday.

The Wisconsin congressman says that he "never would have done that in the first place." He blamed Obama for making the original proposal.

He also says he voted to repeal the president's health care law, which would repeal the Medicare cut.

AP