Kentucky Sen. Rand Paul promised the healthcare plan proposed by House GOP leadership would not pass the Senate and become law because it's just "Obamacare lite."

Paul told Fox News he has serious problems with the plan, especially the replacement for the Affordable Care Act's individual mandate. Paul said there will still be a mandate, of sorts, in the bill but instead of paying the government a penalty for backing out of a health insurance plan that payment would go to private insurance companies.

"This is, in all likelihood, unconstitutional and could destroy the whole repeal program," he said.

He added, "It's Obamacare lite. It will not pass."

Paul proposed his own healthcare bill to replace Obamacare in January but so far it has not been taken up in Congress. Paul is one of the foremost conservative voices who have promised to repeal President Obama's signature law and replace it with a market-based system.

He said the plan proposed by the House GOP leadership relies too much on Obamacare's principles. The taxes under the Affordable Care Act stay in place for another year, the individual mandate is still there but in a different form and the so-called "Cadillac tax," a 40 percent tax on employer-based healthcare plans with more than $10,200 premiums, stays in place forever, he said.

He said the bill doesn't do enough to reform entitlement programs that are setting up the country for a financial crisis in the future.

"I don't think that's a realistic way to look at the entitlement programs," he said.