New Update

In a growing acknowledgment that Paul Kanjorski is indeed vulnerable this fall, CQ Politics updated the race from "Safe Democrat" to a weaker incumbency advantage at "Lean Democrat."

It appears CQ was initially reluctant to make the race upgrade:

"CQ Politics initially was hesitant to include Pennsylvania 11 among the ranks of competitive races, though, in part because the NRCC also heavily promoted Barletta’s candidacy against Kanjorski in 2002, when he lost by the substantial margin of 56 percent to 42 percent."

However, it seems the DCCC's ad campaign in the district ("political parties don’t spend money in districts where they expect easy wins") and Barletta's ability to draw district-wide recognition ("it appears he’ll have the resources to wage a credible campaign") have been the two largest factors behind CQ's decision.

I would also add Kanjorski's willingness to begin airing his own television ads before Independence Day and his reluctance to debate Barletta enhance the perception that Kanjorski is nervous about his reelection chances.