Sean Trende lists some reasons the race to replace Barney Frank in Congress could be competitive, since redistricting made the district more suburban and potentially more Republican:

Frank’s would-be Democratic successor will find him- or herself running in a district that barely went for Democrat Deval Patrick (who won statewide by six points) in 2010 and that gave Republican Brown a 10-point win. The district has also added the hometown of Richard Ross, Scott Brown’s successor in the state Senate, while retaining the home of Sean Bielat, who last year gave Frank his only truly difficult race in decades.

Brown’s narrow win in Frank’s old district is what gave Bielat the impetus to run and made some national Republicans take the race seriously. Any Republican running for this open seat, however, will face two major problems in 2012: Barack Obama will be at the top of the Democratic ticket in 2012 — the president remains popular in Massachusetts — and Brown will be in a tough reelection fight. Massachusetts Republicans may well put all their eggs in Brown’s basket.

The best case scenario for a Republican who would succeed Frank is Brown pulling away from his Democratic challenger by the fall of next year and a GOP presidential nominee — Mitt Romney is the likely candidate here — who can keep Obama below 60 percent statewide. It’s a real long shot, but then so was taking Ted Kennedy’s Senate seat.