President Trump backed House Republicans’ proposal to repeal and replace the Affordable Care Act, but conservative opposition threatens to derail the plan.

A deluge of conservative opposition Tuesday threatened to derail House Republicans’ proposal to repeal and replace the Affordable Care Act, putting the plan’s proponents on the defensive despite President Donald Trump’s public support for the overhaul. Mr. Trump backed the House GOP legislation unveiled Monday night, but left open the possibility that it could require changes. “Our wonderful new healthcare bill is now out for review and negotiation,” he said in a tweet Tuesday morning. Health and Human Services Secretary Tom Price sent a letter Tuesday endorsing the legislation. But swift conservative opposition immediately jeopardized the bill, which can afford few defections in Congress to gain passage. Republicans can’t lose more than two GOP votes in the Senate and 22 in the House, assuming no Democrats support it. A blizzard of conservative groups put out statements criticizing the legislation within hours of its release and lawmakers amplified their concerns.

“We promised the American people we would drain the swamp and end business as usual in Washington. This bill does not do that,” Sen. Mike Lee (R., Utah) said Tuesday. “It is a missed opportunity and a step in the wrong direction.” Under the plan unveiled by two House committees Monday night, Republicans would repeal much of the 2010 health law and replace it with a system centered on refundable tax credits tied to an individual’s age and income. The tax credits, which would supplant the ACA’s subsidies, are aimed at helping Americans buy insurance if they don’t get coverage at work. The House GOP plan would also immediately end the requirement that most Americans have health coverage or pay a penalty, as well as a mandate that larger employers provide health insurance to workers. It would repeal most of the health law’s taxes starting in 2018 and freeze funding in 2020 for the 31 states that expanded Medicaid under the law.

But some Republicans said they were uncomfortable with a GOP proposal that they said hewed too closely to the ACA, often called Obamacare. Both cover pre-existing conditions, provide tax credits and tax generous employer health plans. “This is Obamacare light,” Sen. Rand Paul (R., Ky.), said on Fox News. “It will not pass.” There are many stark differences between the existing health law and the House proposal, including a freeze on federal funding for Medicaid expansion and less financial assistance for low-income people. But conservative Republicans are balking at the similarities because they want to follow through on an election pledge to topple the health law and worry the House proposal doesn’t go far enough.

Rep. Justin Amash (R., Mich.) labeled the new plan “Obamacare 2.0” in a tweet. FreedomWorks, a conservative group, called it “Obamacare Lite,” saying Tuesday that the tax credits would amount to a “new entitlement.” The bill also drew resistance from a bevy of other conservative groups, including the Club for Growth, Freedom Partners, Americans for Prosperity and Heritage Action, the political arm of the Heritage Foundation. The chairmen of the two committees that drafted the bill defended it Tuesday. The House Ways and Means and Energy and Commerce committees are expected to begin debating the measures on Wednesday. “We’re going to help low and middle-income Americans access affordable, quality health care with a monthly tax credit that’s immediately available,” House Ways and Means Chairman Kevin Brady (R., Texas) told reporters Tuesday. Mr. Brady said the House GOP plan wasn’t a rehash of the 2010 health-care law. “This is Obamacare-gone,” he said.

Democrats said their analysis showed it was clear that the GOP plan means far fewer people would receive insurance than under the Affordable Care Act. “After seven years of campaign promises, congressional Republicans still do not have a plan to replace the Affordable Care Act. Instead, they’ve released two bills that will lead to higher costs, lower-quality care and lost coverage for millions of Americans,” said Rep. John Yarmuth of Kentucky, the top Democrat on the House Budget Committee. “That is why House Republicans are trying to rush the bills to the floor with as little debate as possible and with no analysis from the nonpartisan Congressional Budget Office.” The bills must have a cost estimate by the time they arrive at the Budget Committee, expected next week. That committee will combine the separate bills from the two House panels so that they can take advantage of a special process tied to the budget known as reconciliation.

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