Republicans appear to have a real opportunity to take over the seat of the late Rep. John Murtha's (D-Pa.), as another poll shows their candidate in the lead.

The Research 2000 poll for the liberal website Daily Kos has businessman Tim Burns (R) leading former Murtha aide Mark Critz 46-40. It's the biggest lead yet for Burns, who edged Critz 44-41 in a recent Public Policy Polling (D) survey.

The newer poll backs up several key data points from the PPP poll, particularly how unpopular President Obama is in the district. R2000 has Obama's favorable rating at just 38 percent, with 55 percent unfavorable. And Obama isn't just unpopular: Among those 55 percent, more than half say their opinion of the president is "very unfavorable."

Voters there also want to repeal the healthcare bill by a 48-34 margin. Critz was against the bill but has also said he is against repeal.

Democrats might have an advantage with the race being on the same day (May 18) as some hotly contested primaries on their side. But fighting that kind of environmental headwind could be tough to overcome even with the best intangibles.