Many state legislative chambers that had long been held by Democrats have gone Republican in recent years, though West Virginia remains a notable holdout.
Rahall, who was first elected nearly four decades ago, represents a district that went 65 percent for Mitt Romney in the 2012 presidential election. Despite holding conservative territory, Rahall has often avoided serious challenges and defeated state Del. Rick Snuffer (R) 54 to 46 last year.
But the recent history of party-switchers is not good. Rahall himself easily beat another party-switcher, former state Supreme Court justice Spike Maynard, in 2010.
That same year, Rep. Parker Griffith (Ala.) lost a GOP primary and Sen. Arlen Specter (Pa.) lost a Democratic primary after switching parties.
West Virginia Democratic Party Chairman Larry Puccio made clear that Democrats will cast Jenkins as an opportunist.
“After years of supporting Congressman Rahall, it is clear Evan Jenkins is loyal only to the dollar," Puccio said. "When Washington Republican money came a knockin', Jenkins went a walkin'.
“It is a shame that Evan is allowing money and politics to influence his misguided attempt to further his personal political ambition.”
Prior to Jenkins, Republicans unsuccessfully attempted to recruit state Sen. Bill Cole into the race.
The Cook Political Report rates Rahall's seat as "likely Democratic."