The Harrisburg Patriot-News reported the Keystone poll of 459 registered voters found Casey with 44 percent of the vote and Santorum with 43 percent and 13 percent undecided. The margin of era is 4.6 percent.
A Quinnipiac University poll of 1,250 voters released last month found an unidentified Democrat with 46 percent of the vote and Santorum at 41 percent, with 11 percent undecided and a 2.8-point margin or era.
Casey, the son of popular former Gov. Robert Casey, is the presumptive nominee as other potential Democratic challengers to Santorum have stepped aside at the request of Democratic leaders.
Santorum is one of the lawmakers Democrats are targeting for defeat in 2006.