Story highlights Senate Republicans unveiled a modified version of the bill Thursday

Collins said the bill would lower spending on Medicaid by about three-quarters of a trillion dollars by 2026

(CNN) The Congressional Budget Office is not expected to release its analysis of the revised Republican health care bill Monday, a Senate GOP aide tells CNN.

The CBO was widely expected to release the report Monday, and it is now unclear when that assessment will come out.

McConnell needs support from 50 of the 52 GOP senators to pass it, and two GOP senators, Maine's Susan Collins and Kentucky's Rand Paul, have already said they won't vote for the legislation. The news came after Senate Majority Leader Mitch McConnell announced Saturday evening he would postpone a vote on the bill because Republican Sen. John McCain is recovering from surgery in his home state of Arizona this week. McCain's absence from the Senate would have imperiled the bill becauseMcConnell needs support from 50 of the 52 GOP senators to pass it, and two GOP senators, Maine's Susan Collins and Kentucky's Rand Paul, have already said they won't vote for the legislation.

Collins said on CNN's "State of the Union" Sunday that she remains opposed to taking up the Senate Republican health care bill because it would hurt some of the people who need care the most.

"This bill would impose fundamental, sweeping changes in the Medicaid program," Collins said. "Those (changes) include very deep cuts that would affect some of the most vulnerable people in our society, including disabled children, poor seniors. It would affect our rural hospitals and our nursing homes."

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