Chuck Todd ranks the U.S. Senate seats most vulnerable to a party change in 2006. The top five:
Rhode Island: Sen. Lincoln Chafee (R). "There's no incumbent senator sporting more precarious poll numbers than Chafee."
Pennsylvania: Rick Santorum (R). "The race between Santorum and Democrat Bob Casey Jr. will be this cycle's premiere campaign, the one national reporters parachute into from time to time to gauge what the nation's 'mood' is."
Minnesota: Open seat with Mark Dayton (D) retiring. "Ninety-nine times out of 100, a party is better off with an incumbent seeking re-election. Meet the one-time exception."
Nebraska: Ben Nelson (D). "Basically any Republican who isn't a complete embarrassment can do well against Nelson."
Tennessee: Open seat with Bill Frist (R) retiring. "We're going to do our best to get folks to calm down over Rep. Harold Ford Jr. The coverage he gets for his campaign suggests someone who seems destined to back out. And yet, he's only backed out of one race."