Five of the six voted for Obamacare (Manchin was elected in 2010).

Via WaPo:

Sen. Jeff Merkley (D-Ore.) has signed on to Sen. Mary Landrieu’s (D-La.) bill that seeks to allow people whose insurance plans have been canceled to keep them, becoming the sixth Democratic senator to back the effort.

Merkley has signed on as a co-sponsor, joining Landrieu and Sens. Dianne Feinstein (D-Calif.), Kay Hagan (D-N.C.), Mark Pryor (D-Ark.) and Joe Manchin (D-W.Va.).

All but Feinstein and Manchin face reelection in 2014.

Merkley isn’t considered a top GOP target, but he recently drew a challenge from Dr. Monica Wehby, who Republicans hope can put a blue state in play if Obamacare’s problems continue into the election year.