Kentucky: Rand Paul (R), Running... Safe R
He says he's running for reelection, yet he also says he's thinking about running for president, even though it's legally impossible for him to do both at the same time. He hasn't exactly clarified how he plans to deal with that fact.
Yeah, quite confused by that. Could he cancel for file of re-election of Kentucky? If so, its Likely R without him, Safe R with him.
The Kentucky presidential primary and US Senate primary are at the same time. He can't legally be on the ballot for both, and the filing deadline is in February 2016, very early in the presidential primary process. So what is Paul going to do? Run for president until February, and then drop out to run for reelection? That might work for third tier candidates like Duncan Hunter, who can get away with planning for failure. But Paul will likely be a top tier candidate, so I can't see him doing that unless his presidential campaign is really struggling.
The one way around it would be if he runs for president in 49 states, but not in Kentucky. Doesn't put himself on the presidential ballot in Kentucky, but runs for senate there, while running for president everywhere else. But that would look ridiculous.
(Rubio doesn't have this same problem, because the presidential and senate primaries are separate in Florida, and Rubio wouldn't have to file for reelection until May, when the presidential nominating contest is nearly over. No GOP presidential nomination contest has remained contested that late since 1976, so he should be able to run for president, see if he wins the nomination, then jump into the senate race if the presidential race doesn't work out.)