That would be Senator Byron Dorgan (D-ND), who’s held his current seat since 1992. Dorgan won his last re-election in 2004 by a margin of 36%. Now? He trails Republican Governor John Hoeven by a margin of 55-36% — a 19-point loss. Hoeven hasn’t even declared his candidacy or publicly expressed interest in the seat yet.

Why the sudden change of heart by North Dakota’s electorate? It might have something to do with Dorgan’s support for Democratic attempts to socialize the nation’s health care industry. Or his crucial votes that allowed the deficit to reach $1.4 trillion for FY2009. Or maybe his vote in favor of the $787 billion “stimulus” package that hasn’t stimulated anything but liberal special interests.

You know, any of that.