[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2010/images/04/15/art.critz.youtube.jpg caption="Republicans are running an ad against Democratic candidate Mark Critz that links him to health care reform."]Washington (CNN) - With just over a month to go before the May 18 special election to fill the House seat formerly held by the late Rep. John Murtha, political ads are starting to light up the airwaves in Pennsylvania's 12th congressional district.
Republican Tim Burns and Democrat Mark Critz are both being attacked in TV spots financed by national party committees.
On Thursday, the Democratic Congressional Campaign Committee released an ad alleging that Burns would raise taxes. As the ad's narrator tells it, "Southwestern Pennsylvania is hurting, but millionaire Tim Burns would make things even worse."
The National Republican Congressional Committee went on TV earlier this week with an ad painting Critz as too liberal for Pennsylvania because of his support for federal health care legislation.
"Americans said no to government run health care, but Congress and liberals like Mark Critz didn't listen," that ad's narrator claims. "He'll put the liberal agenda before Pennsylvania."
Though a GOP win in the district would be the first in many years, it would not be a complete suprise. Murtha, who steered millions of federal dollars back to his home district, rarely had any serious challenges in his 18 re-election contests. But the district, which stretches from Cambria County in west-central Pennsylvania down to the southwestern corner of the state, is conserative-leaning one.
In the 2004 presidential election, Sen. John Kerry won Pennsylvania's 12th Congressional District by 2 points. But Sen. John McCain narrowly edged out Barack Obama in the district in 2008, even though Obama carried the state by 10 percent.
- CNN's Paul Steinhauser contributed to this report