Asked if the massive bill containing most of Trump's domestic agenda could clear the GOP-led senate as written, Paul told reporters that's a question mark.
"I think it's close. There are three or four of us who are very concerned about the spending and the debt ceiling," he said Tuesday.
As a holdout on the bill, Paul has found himself on the receiving end of Trump's ire. The president attacked the Kentucky lawmaker online writing: "He loves voting ‘NO’ on everything, he thinks it’s good politics, but it’s not," adding, "never has any practical or constructive ideas."
The senator laughed off the comments saying the two-year $5 trillion debt ceiling increase is a deal-breaker for him.
"It's one of the most important debates of our time, and this is a debate over whether or not a country can have $36 trillion in debt, whether we can have interest payments over a trillion dollars," he said. "I don't make it personal at all. I like the president, supported the president. In fact, I'm for the tax cuts. I am for a lot of the bill, but I can't, in good conscious, give up every principle that I stand for."
Republicans can only afford to lose three votes on their side of the aisle if they want to pass the bill in the Senate. The current version cleared the House by a razor thin margin — just one vote — and senators say they want to see changes.