The mayor of Boston doubts that Scott Brown can lose next year:

Boston Mayor Thomas Menino (D) says no one from the ranks of his party will be able to beat Sen. Scott Brown (R-Mass.) in 2012.  "There's nobody that can beat him," Menino said of Brown, who must run for a full six-year term in 2012 after his special-election victory to replace the late Sen. Edward Kennedy (D-Mass.).  Menino made the comments in an interview with the Boston Herald, in which he talked about his recovery from emergency knee surgery and his own political future. The paper notes that Brown phoned Menino after his recent surgery.

The only recent poll from Massachusetts came in early December from PPP, which found Scott Brown's net approval rating at +24 (53 percent approve to just 29 percent disapprove). Impressively, Brown pulled in 35 percent approval from self-identified Democrats, which is a necessity for a positive rating in the Bay State.

Brown's biggest problem is going to be Barack Obama. He'll have to run for reelection with the presidential race at the top of the ticket, meaning that his only path to reelection will depend on a significant crossover vote. This explains why Brown has only been a sometimes-ally of conservative policy initiatives in the Senate. That trend is sure to continue.

Does that make him a RINO, or Republican-in-name-only? It depends on your perspective. If you compare him to Jim DeMint, then definitely. On the other hand, compare him to the kind of liberal Democrat who would surely replace him if he were to vote the conservative line without exception, then no way.