After years of facing little to no serious competition for his seat, Frank confronted a major challenge from Bielat in 2010, but still ended up 11 points ahead.

The district was made slightly more conservative this year in redistricting, but Democrats still have the clear advantage.

Another Republican, physician Elizabeth Childs, had already entered the GOP primary before Frank announced his retirement on Monday. About a dozen Democrats are also considering a run for the seat.