Utah Sen. Mike Lee said Senate Republicans should jump back on board a plan they all backed 18 months ago and vote to repeal the Affordable Care Act in full if they cannot find a deal on the Senate GOP healthcare bill.

Lee said on CBS Sunday that Republicans were fine with repealing the law in full in December 2015 and should do the same if they find that an agreement on the Better Care Reconciliation Act is out of reach.

"What we ought to do is get back to what I've been suggesting for the last six months, and that is to push full repeal and then go through a step-by-step process to determine what comes next," he said.

Lee is one of the conservative holdouts who has refused to back the Senate Republican healthcare plan to repeal and replace parts of Obamacare. He's found the bill as written is not conservative enough and doesn't go far enough in fulfilling the campaign promise Republicans have run on since the bill passed in 2010.

President Obama vetoed a measure passed by the Congress repealing Obamacare in full in December 2015, and Lee has pressed for the same bill to be taken up by current lawmakers.

He said there's a chance the Better Care Reconciliation Act will collapse under its own weight, which he says is happening to Obamacare right now.

"If we adopted a measure repealing Obamacare and put a delayed implementation measure in there ... I think it's easier," he said. "Sometimes when you lump too many things into one piece of legislation, you doom its chances of success and that might be where we are right now."