Kentucky Sen. Rand Paul said he can’t imagine supporting anyone other than President Trump in the 2020 election, but paused for a long time when asked if a Republican should challenge Trump in the primary.

Paul, on MSNBC, paused for a few seconds to gather his thoughts when asked if another Republican should mount a challenge to Trump in the next election.

“I think no one can stop primaries from happening, and there could well be a primary that happens. Before you get to that, you need to know, is President Trump running for re-election,” Paul said. “You won't know that until you get into the second, third year of his presidency. At this point, I can't see myself supporting anyone but President Trump because I think he's given us the most conservative cabinet we've seen since Reagan.”

“We've repealed regulations for the first time. Gave us a great Supreme Court justice and I'm hoping he gives us a couple more if we have retirements. I see the glass as half full. Doesn't mean I agree with him on everything. There will be people that if we can end the Afghan war, that's who I would support. I don't think that's going to be an alternative to president trump. I like to accentuate the positive, and I would support him.”

Paul has been a challenging vote for Trump to count on in the Senate. He’s proved at horn in the side of Republican leadership on attempts to do reform or repeal parts of the Affordable Care Act and is not seen as a sure thing when it comes to a vote on tax reform.

When pressed by host Kasie Hunt, Paul refused to say if he thought a primary challenge to Trump would be good for the Republican Party.