Sen. Rand PaulRand PaulGOP senators pitch alternatives after House pulls ObamaCare repeal bill Rand Paul takes victory lap on GOP health bill Paul: Pence should oversee Senate ObamaCare repeal votes MORE (R-Ky.) on Thursday warned that Senate Majority Leader Mitch McConnellMitch McConnellThe Memo: Winners and losers from the battle over health care GOP senators pitch alternatives after House pulls ObamaCare repeal bill Under pressure, Dems hold back Gorsuch support MORE (R-Ky.) faces a tough reelection fight.

"My guess would be that the general election is fairly close," Paul told The Herald-Leader of McConnell's prospects.

Paul, who has endorsed the GOP leader for reelection, said he he believes McConnell will defeat primary challenger Matt Bevin, saying he doesn't believe the primary is "particularly close at this point."

McConnell is viewed with suspicion by many conservatives who have balked at some of the deals he has negotiated with Democrats.

Paul complimented Bevin as a "good, honest, Christian man" on the day he filed his candidacy, prompting some to wonder about Paul's commitment to McConnell.

Assuming he wins the primary, McConnell is expected to face Kentucky Secretary of State Alison Lundergan Grimes in the general election. Grimes is a highly-touted recruit who's expected to raise substantial sums and, as a young female candidate she could create a strong contrast with McConnell.

Multiple polls have shown her running even or slightly leading the Senate minority leader, who remains unpopular in his home state. Democrats are looking to Kentucky as their top pickup opportunity this cycle.