When Sen. Ben Nelson took the money, voted for cloture on the health care bill, and ran, the idea that there’s any room for moderates in the Democratic Party may be an anachronism.

Case in point: Freshman Rep. Parker Griffith, a physician from Alabama and a member of the Blue Dog Coalition, announced today he’s switching from Democrat to Republican.

By joining the GOP, the party that has not held his congressional district since 1866, Griffith cited the Senate health care bill as a reason for leaving the Dems.

As The Corner points out, in the past few days, four Blue Dogs have announced they would not seek re-election. (Including Bart Gordon of Tennessee, chaiman of the House science and technology committee, who holds the House seat previously occupied by Al Gore Sr. and Jr., and who ran essentially unopposed in 2008.)

If trends continue, Democratic losses during Barack Obama’s midterm election may outpace Bill Clinton’s.