Republican Sen. Bill Cassidy said Monday that the Congressional Budgeting Office score on the Senate healthcare bill makes him "more concerned" about the GOP plan.

"It makes me more concerned," the Louisiana senator said shortly after the score was released. "I've been uncommitted — and I remain uncommitted, I mean just deadline uncommitted — but it certainly makes me more concerned, it makes me want to explore this more."

The CBO score said the Republican healthcare bill meant to repeal and replace Obamacare would leave 22 million more people uninsured over a decade and would mean a $321 deficit reduction.

Cassidy previously said in a statement that he would "study the bill to determine whether it fulfills President Trump's campaign promises to lower premiums, maintain coverage and protect those with preexisting conditions without mandates."

The Republicans have a very narrow margin to get the Senate bill passed, with room for only two defections. Five Republican senators, not including Cassidy, have said they do not support the bill in its current form.