Republican Sen. Susan Collins disagrees with Vice President Mike Pence's analysis that the Senate GOP's healthcare bill would strengthen Medicaid for the most vulnerable.

"This bill would impose fundamental sweeping changes in the Medicaid program and those include very deep cuts. That would affect some of the most vulnerable in our society, including disabled children, poor seniors. It would affect our rural hospitals and nursing homes, and they would have a very difficult time even staying in existence," she said on CNN's "State of the Union."

On Friday, Pence told governors he and Trump believe the Senate healthcare bill "strengthens and secures Medicaid for the neediest in our society."

The bill, known as the Better Care Reconciliation Act, would roll back Obamacare's expansion of Medicaid in states that allow all low-income residents to be covered.

The Congressional Budget Office estimates these changes would result in cuts of $772 billion in federal spending on Medicaid, and would shed 15 million people from the program.

"You can't take more than $700 billion out of the Medicaid program and not think that it's going to have some kind of effect," Collins said.

She added there are eight to 10 Republican senators who have "serious" concerns about their party's bill and she doesn't know whether it will pass.

"I do know this: We should not be making fundamental changes in a vital safety net program that's been on the books for 50 years … without evaluating what the consequences will be," Collins said.

Kimberly Leonard contributed to this report.