Though Pennsylvania U.S. Sen. Bob Casey has long been known as an anti-abortion Catholic, he's among six senators targeted in a hard-hitting radio ad by a newly-formed political group called "Defending Our Faith."

"Why is he supporting a president who is persecuting the Catholic church?" an announcer says of Casey in the ad. You can hear it by playing the audio above.

The ad refers to the Obama administration's requirement that employer-based insurance plans cover contraceptive services. Matt Mackowiak, a spokesman for the group said the ads are airing in five Pennsylvania media markets, but not Philadelphia. He woudln't say how big the ad buys are, but that the buy is "healthy enough to make an impact." He said they'd be followed by TV Ads.

Casey campaign spokesman Larry Smar called the campaign "just another untrue negative attack with no basis in reality."

Plenty more where that came from

The ad is just one of a shower of messages raining on Pennsylvania from outside groups in the new anything-goes world of political fundraising and messaging.

Keegan Gibson of Politics Pa reports on an ad supporting Casey and attacking his opponent Tom Smith apparently backed by $500,000 from a super PAC backing Democratic Senate candidates. You can see the ad above. Smith spokeswoman Megan Piwowar called it "further evidence of Bob Casey's sputtering campaign and crumbling support."

And Democratic Attorney General candidate is actually denouncing an ad attacking her opponent David Freed sponsored by a Washington-based political committee. Weeks ago, Kane was denouncing Freed for not denouncing an inaccurate ad attacking her by a Washington-based Republican group, if you can follow that.

But the most interesting piece I saw on this phenomenon lately is a story in Wednesday's New York Times about how even many Republican lawmakers are considering new campaign regulations after seeing an onslaught of negative ads. Read it here.