I'll start it off seeming how it's the Senate blocking most pro second legislation (to get back our rights):

Conrad Burns – Montana
Main article : Montana U.S. Senate election, 2006

Senator Burns faced a strong challenge from current Governor Brian Schweitzer in 2000, being re-elected by a mere 3% in a state that went for Bush twice by margins of over 20%. This, combined with the increasing strength of the state Democratic party and accusations of ethical issues related to the Jack Abramoff scandal, could make this a competitive race. Burns is also rumored to be considering retirement. State auditor John Morrison has filed papers to run for the Democratic nomination, and popular state senate president Jon Tester has announced his candidacy. While recent polling have suggested that Conrad Burns has a commanding lead over his Democratic challengers, an even newer one shows Burns with only a 45% approval rating, the second lowest in the Senate, and the highest disapproval rating in the Senate, 46%, making him one of only two Senators to have a negative Net Approval rating (approval rating minus disapproval rating

Is it true Burns could lose?