Nancy Pelosi’s majority in the House of Representatives just got a little smaller. And the coalition of “Blue Dog” Democrats has lost a member.

Parker Griffith (D/R-AL), the represenative from the fifth district of Alabama (the northern part of the state, including Huntsville), will announce a switch today from Pelosi’s Democrat majority to the GOP, in what is a small coup for the minority party but not a particularly surprising development.

Griffith, a radiation oncologist by trade, was a “no” vote on the House’s health-care bill last month. He’s been a relatively loud voice opposing Pelosi’s Speakership and had threatened not to support her as the Democrat Party’s head in the House at the next vote. Griffith heard a mouthful during August town hall meetings, at which he was booed despite declaring his opposition to Obamacare.

Griffith’s district went 61 percent for John McCain last year, though in switching to the GOP he’s the first Republican to hold that seat in Congress. He’s been a relatively solid conservative vote this year – Griffith was one of only 11 Democrats to oppose the stimulus bill, he opposed the cap-and-trade bill and he was a “no” vote on Pelosi’s financial regulatory bill.

Griffith goes into next year’s election cycle with $619,000 in the bank, including $10,000 from Steny Hoyer’s PAC and $4,000 from Pelosi’s. It’s highly likely that he’ll have a Republican primary challenger, however, as several candidates had been lining up to challenge him as a Democrat.

Griffith’s switch now gives the GOP 178 House members, and the magic number for the Republicans to retake the Speakership in next year’s elections is 40.