The Senate's Obamacare replacement bill would lead to 22 million more Americans uninsured in 2026, while average premiums are expected to fall after climbing at first, according to a Monday report from the nonpartisan Congressional Budget Office.

The CBO's estimate of the plan's effect on the number of uninsured Americans could influence whether Republican senators support it, as GOP leaders walk a thin line in trying to win the votes needed to pass their plan. The estimated growth in the number of uninsured Americans is slightly lower under the Senate plan than the bill that passed the House last month, which the CBO said would lead to 23 million fewer covered in 2026.

Average premiums for single individuals would rise by 20 percent and 10 percent in 2018 and 2019, respectively, relative to current law, according to the CBO. By 2026, average premiums in most of the country are expected to be about 20 percent lower under the plan than they would be under current law.

Senate Republicans last week released a draft of their secretive Obamacare replacement bill, called the "Better Care Reconciliation Act of 2017." The plan would repeal Obamacare taxes, restructure subsidies to insurance customers that are based on their incomes and phase out Medicaid's expansion program. It contains some key differences from the version the House passed last month.

Shortly before the CBO released the score, Senate Republicans unveiled a revised version that appears aimed to deter younger, healthier people from dropping insurance. The updated bill would impose a six-month waiting period on individuals who buy insurance but let their coverage lapse for more than 63 days in the prior year.

That provision, an apparent response to Obamacare's individual mandate, would start in 2019. It would "slightly increase" the number of people with insurance in the 2018 to 2026 period, the CBO said.

Before the CBO released the score for the Senate plan, five GOP senators said they will not back it in its current form. Republicans, who control 52 seats in the Senate, can only lose two votes to pass the plan. They face difficulties in winning over skeptical senators, as tweaks to appease conservatives could alienate moderates, or vice versa.

Here are some of the key conclusions from the CBO report: