Four million people would lose employer-provided insurance coverage in 2018 if the Senate's plan to repeal ObamaCare became law, the Congressional Budget Office (CBO) projected on Monday.

The nonpartisan budget analyst attributed the drop to the GOP's plan to repeal ObamaCare's two central mandates: the requirement to have health insurance and the requirement that most large employers provide it.

"Under current law, the prospect of paying the employer mandate penalty tips the scale for some businesses and causes them to decide to offer health insurance to their employees. Thus, eliminating that penalty would cause some employers to not offer health insurance," the CBO wrote.

ADVERTISEMENT

"Similarly, the demand for insurance among employees is greater under current law because some employees want employment-based coverage so that they can avoid paying the individual mandate penalty. Eliminating that penalty would reduce such demand and would cause some employers to not offer coverage or some employees to not enroll in coverage they were offered."

The number of people losing employer-provided coverage under the Senate’s legislation is an increase from the bill passed by the House last month. The CBO in May assessed that 2 million people would lose employer-provided coverage in 2018 under the House legislation.

Looking more broadly at the insurance market, CBO projected that 15 million more people would become uninsured next year under the Senate bill, with a total of 22 million people becoming uninsured over the next 10 years.

The analysis comes as Senate Republicans face an uphill battle to pass the long-awaited legislation. Five senators have said they oppose the bill in its current form.

Republicans, with a 52-seat majority, can afford to lose two senators and have a tiebreaker by Vice President Pence.