WASHINGTON -- Constituents of Rep. Tom MacArthur would fare the worst in New Jersey under House Republican health care legislation that he played a major role in passing.

A report by New Jersey Policy Perspective said the number of residents in the 3rd Congressional District without health coverage would grow by 112 percent, adding 40,923 people to the ranks of the uninsured by 2026.

Overall, 540,000 fewer New Jersey residents would be covered under the lose coverage under the House Republicans' health care legislation, according to the report by NJPP, a progressive research group.

Under the original Republican bill, which was pulled from the House floor in March due to lack of support, the ranks of the state's uninsured would have grown by 500,000.

"This new analysis makes abundantly clear that even calling the House-passed bill a 'health bill' at all is a bit misleading," NJPP Vice President Jon Whiten said. "This legislation will do a lot of things -- chiefly make New Jersey's wealthiest taxpayers much, much wealthier while stripping affordable coverage from many of the rest of us -- but there's no way it will improve the health of New Jerseyans."

MacArthur spokeswoman Camille Gallo derided the findings as "another dumpster fire report from a liberal special interest group" and said the lawmaker was trying to preserve health coverage.

"The truth is simple: The individual marketplace is on the brink of collapse, premiums are soaring, deductibles are through the roof, insurers are leaving in droves, and choices are evaporating," Gallo said.

"Congressman MacArthur doesn't waste his time pontificating about special interest group reports," Gallo said. "He is busy working on fixing the big problems facing our nation, which many in the media and liberal special interest world would prefer to ignore."

The measure remains very unpopular. Just 32 percent of U.S. adults in a CBS News survey released Tuesday supported the House Republican bill, while 59 percent opposed it.

The Republican bill would cut federal spending in New Jersey by $28 billion over 10 years, leading to the loss of 54,000 jobs, the report said.

The state's uninsured rate, now 9.8 percent, would rise to 14 percent in 2026, the NJPP report said. Much of the increase would be due to Medicaid spending reductions in the House GOP bill, which President Donald Trump embraced despite a campaign promise to oppose cuts to the program for the poor, elderly and disabled.

The House Republican bill would cut Medicaid spending by $834 billion over 10 years, and use most of the savings to fund tax cuts for corporations and wealthy Americans. The wealthiest 5 percent of New Jersey households would get $13 billion in tax cuts over 10 years, NJPP said.

States would receive a fixed sum each year rather than a flexible amount depending on their number of recipients, and those states like New Jersey that expanded the program would no longer get enhanced federal funding for those enrolled after 2019 nor for those who temporarily leave the Medicaid program and return.

In New Jersey, the uninsured population would double in two of the other 12 congressional districts, including the 11th District represented by Republican Rep. Rodney Frelinghuysen, who changed his vote and joined MacArthur as the only Garden State lawmakers supporting the House Republicans' health care legislation, NJPP said.

The report was issued as Senate Republicans, meeting in secret without any public hearings or discussion, prepared to offer their own health care bill.

"Given the incredible harm the House-passed bill would do to states around the country, it's alarming that the Senate appears to be adopting most of the major provisions," said Raymond Castro, NJPP's director of health policy. "This is a big step backward for the health of New Jerseyans and Americans overall."

Nationally, 23 million fewer Americans would have insurance under the American Health Care Act than under the Affordable Care Act that it would replace, according to the Congressional Budget Office.

In addition, MacArthur's amendment enabling states to get waivers from federal requirements that insurers offer certain benefits and cannot charge more for customers with pre-existing conditions could leave sicker individuals "unable to purchase comprehensive coverage with premiums close to those under current law and might not be able to purchase coverage at all," the CBO said.

Health care experts have said the marketplaces were stable in most states and that existing subsidies insulated most policyholders from higher premiums.

"As far as everyday people are concerned, they're not really seeing these sticker prices," Cynthia Cox, associate director of health reform and private insurance for the Kaiser Family Foundation, which studies health care, told NJ Advance Media in May.

Insurers have said they were pulling out because of the uncertainty brought about by Republican repeal efforts and because Trump has refused to approve $7 million in cost-sharing payments to hold down out-of-pocket expenses for low-income Americans.

Anthem Blue Cross Blue Shield, for example, cited "the lack of certainty of funding for cost-sharing reduction subsidies" and "an increasing lack of overall predictability" when it pulled out of most markets in Ohio.

And America's Health Insurance Plans, the Washington-based trade group for health insurers, called the uncertainty over cost sharing the "single most destabilizing factor in the individual market."

Meanwhile, the New York-based health insurance company Oscar wants to re-enter the New Jersey market that it earlier withdrew from.

Jonathan D. Salant may be reached at jsalant@njadvancemedia.com. Follow him on Twitter @JDSalant or on Facebook. Find NJ.com Politics on Facebook.