The Senate Republican health care bill would increase the number of uninsured Americans by 22 million over a decade to 49 million, the Congressional Budget Office said Monday. This estimate likely will increase the challenges for Majority Leader Mitch McConnell of Kentucky in trying to pass the bill before the July Fourth recess.

In comparison, the version the House passed May 4 would increase the uninsured population by 23 million over a decade, the CBO said last month. The Senate bill would save $321 billion over a decade, more than the House bill’s $119 billion reported by the CBO last month.

The CBO’s conclusions will exacerbate McConnell’s hurdles in gaining unity among his fractured GOP conference. Several Senate Republicans raised doubts in recent days about whether they would vote for a motion to proceed to the bill if McConnell tries to hold it Tuesday or Wednesday.

The $202 billion in savings above the House plan could give McConnell and other supporters substantial flexibility to make deals and win the support of more moderate members of the conference. Those lawmakers, however, might insist on updated CBO scoring before voting for the motion to proceed.

The Senate health care bill was released last week.