The CBO’s analysis has been awaited as a crucial piece of evidence as McConnell, Ky., and other Republican leaders try to hurry a vote on the bill this week. But they are navigating an expanding minefield of resistance from their own party’s moderate and conservative wings, while Democrats are united against it.

The forecast issued Monday by Congress’ nonpartisan budget scorekeepers also estimates that the Senate measure, drafted in secret mainly by Majority Leader Mitch McConnell and aides, would reduce federal spending by $321 billion by 2026 - compared with $119 billion for the House’s version.

WASHINGTON — Senate Republicans’ bill to erase major parts of the Affordable Care Act would cause an estimated 22 million more Americans to be uninsured in the coming decade — about 1 million fewer than similar legislation recently passed by the House, according to the Congressional Budget Office.


Several moderates have said they will decide whether they can support the Better Care Reconciliation Act based on how it will affect Americans who have gained coverage under the ACA during the past few years, while their conservative colleagues are focused on its impact on the federal deficit.

The fresh figures come as President Donald Trump, in a sharp pivot from the praise he initially lavished on the House bill, is urging the Senate to provide Americans more generous help with health insurance. On Sunday, the president repeated during a ‘‘Fox and Friends’’ TV appearance a word he had used in a private White House lunch earlier this month with a group of GOP senators: that the House’s version is ‘‘mean.’’

The CBO has been regarded over its four-decade history as a source of neutral analyses devoid of political agenda. Its current director, Keith Hall, is a conservative economist who served in the administration of President George W. Bush and was appointed to his current role two years ago by a Republican Congress.


Nevertheless, senior Trump aides have repeatedly sought to cast doubt on the budget office’s credibility. ‘‘If you’re looking at the CBO for accuracy, you’re looking in the wrong place,’’ White House press secretary Sean Spicer said on the March day that the budget office issued its cost estimate of a preliminary version of the House GOP’s health-care legislation.

In a statement released Monday evening, the White House said the CBO’s projection ‘‘must not be trusted blindly.’’

The White House says the CBO ‘‘has consistently proven it cannot accurately predict how health care legislation will impact insurance coverage.’’

It says the office has a ‘‘history of inaccuracy,’’ and cites its ‘‘flawed report on coverage, premiums and predicted deficit arising out of Obamacare.’’

While they differ in important details, both the Senate GOP’s plan and the American Health Care Act narrowly passed by House Republicans in May share the goal of undoing central aspects of the sprawling health-care law enacted by a Democratic Congress seven years ago.

Both bills would eliminate enforcement of the ACA’s mandate that most Americans carry health insurance, relying on subtler deterrents to keep people from dropping coverage. The House version would let insurers temporarily charge higher rates, while the Senate added a provision Monday that would let health plans freeze out customers for six months if they let their coverage lapse.

In different ways, both would replace federal subsidies that help the vast majority of consumers buying coverage through ACA marketplaces, instead creating smaller tax credits that would provide greater assistance to younger adults while making insurance more expensive for people from middle age into their 60s.


After two years, both also would end subsidies that now help about 7 million lower-income people with ACA health plans afford deductibles and copays. And both would repeal an array of taxes that have helped to pay for the ACA’s benefits, including levies on health insurers and on wealthy Americans’ investment income.

For the Senate bill, the CBO’s estimates of insurance coverage and federal spending are influenced by the fact that its forecast covers a 10-year window and the legislation’s most profound changes for the nation’s health-care system are tilted toward the latter part of that period.

The bill would, for instance, leave in place the ACA’s expansion of Medicaid through 2020. After that, it would begin a three-year phaseout of the federal money that under the ACA has paid almost the entire cost of adding 11 million Americans to the program’s rolls in 31 states.

That means the extra funding wouldn’t disappear until the mid-2020s - roughly when sharp new restrictions on federal payments for the entire Medicaid program would take effect.

Over the weekend, the senior Democrat on the Senate subcommittee that oversees the CBO said in a tweet that he had asked the budget office to estimate the Senate bill’s effect on insurance coverage over a longer time horizon. ‘‘GOP is hiding the worst Medicaid cuts in years 11, 12, 13 and hoping CBO stays quiet,’’ wrote Sen. Chris Murphy, D-Conn.