Sen. Rand Paul cautioned President Trump against overselling the effects of the Better Care Reconciliation Act because he doesn't think it's going to solve enough of the healthcare system's problems.

The Kentucky Republican told "Fox News Sunday" he wouldn't be promoting the Senate healthcare bill in the way Trump is, promising massive fixes to the system's problems.

"I would caution about overselling what's going to happen," he said.

Paul said the problem with new legislation that tries to shape the system a decade into the future is that American government is too fluid to really commit to such a plan.

"We do things in the first two or three or four years and by the time we get to year seven, eight, or nine, there's a new Congress or a new president and the whole thing goes out the window," he said.

Paul said he won't support the Senate Republican healthcare plan because it keeps too much of the Affordable Care Act and doesn't fix the main problem with the law that's causing it to go into a so-called "death spiral."

Paul said he couldn't support the Better Care Reconciliation Act because it doesn't repeal enough of Obamacare's taxes, mandates, and regulations. He added that Republicans who have written the bill haven't fixed the essential problem: Not enough healthy, young people are signing up for the exchanges to subsidize the sick and older people who need insurance.

"The Republican plan admits it will continue, it just says, ‘Hey guys, we're going to subsidize it,'" he said.

Paul added, "This bill keeps most of the Obamacare taxes, keeps most of the regulations, keeps most of the mandates and creates something Republicans have never been for before and that's an insurance company bailout super fund."

Paul said Senate Republicans should just repeal Obamacare in total if there's no deal to be had on the Better Care Reconciliation Act.

"We should try to repeal this, as many of the taxes, as many of the regulations, as many of the mandates as we possibly can," he said.