It doesn't look like Republican Senator Rick Santorum will be able to pull a rabbit out of the hat. This race remains in the Democrat’s column for our Senate Balance of Power summary.

The incumbent gained five percentage points of voter support since our October 5 survey of the race, and a further point since October 16. But as undecided and other voters break for one of the major-party candidates, Democrat Bob Casey, Jr. has been gaining as well. Thus Casey still leads Santorum by the same thirteen-point margin, now 55% to 42% (see crosstabs).

Santorum loses almost a fourth of the GOP base and a full 25% of conservatives to Casey, who shares the conservative opposition to abortion and gun control. If newly revived concerns about judicial activism and gay unions are helping struggling Republicans elsewhere, that's not the case in Pennsylvania.

Santorum's campaign recently ran an ad attacking Casey's purported weakness on national defense. A nuclear mushroom cloud figured prominently. On a Fox News Sunday appearance, Santorum said his opponent's stance in support of a "comprehensive" bill on illegal immigration means he's soft on terror. The Senator admitted that by the logic of his argument, many of his Republican colleagues and President Bush himself are soft on terror—at least with respect to immigration policy.

All year long, Santorum has been the most vulnerable Senate incumbent. A turnaround seemed possible in August, when he closed the gap and was just eight points shy of the challenger. But that improvement proved fleeting.

Senator Santorum continues to enjoy a higher "very favorable" rating than his opponent, 27% versus Casey's 16%. But Santorum is also viewed "very unfavorably" by 36%. Casey is viewed so unfavorably by 23%.

President Bush's approval rating is at 43% in Pennsylvania. Fifty-seven percent (57%) disapprove of the job he's doing, including 45% who disapprove strongly.

Crosstabs available for Premium Members only.