(Alice Li,Libby Casey/The Washington Post)

The health-care proposal unveiled by Senate Majority Leader Mitch McConnell on Thursday came under immediate attack from conservative and centrist Republican senators as well as industry officials, casting the bill’s viability into doubt even as GOP leaders plan to bring it to a final vote next week.

The 142-page bill, which McConnell (R-Ky.) released after weeks of drafting it in secrecy, drew swift criticism from hard-right senators who argued it does not go far enough in undoing Barack Obama’s signature health-care law, the Affordable Care Act. It also prompted an outcry from centrist senators and medical organizations worried that it takes on the law, known as Obamacare, too aggressively and would lead to millions losing their health care or receiving fewer benefits.

These critics effectively delivered their opening bids in what is expected to be a contentious week of negotiations. McConnell is trying to pass the bill before the July 4 recess, with Republican leaders seeking to quickly learn whether they will be able to fulfill years of promises to roll back the law or whether it’s time to turn to other items on their legislative agenda, such as overhauling the tax code.

No Republican senators definitively said they would vote against the bill, instead focusing attention on the provisions that would need to be changed to earn their vote. President Trump predicted the final product is “going to be great” — but only after some more negotiations take place.

The next big showdown will come early next week when the nonpartisan Congressional Budget Office releases its analysis of the bill. Congress’s scorekeeper is expected to release a comprehensive estimate of how many people could lose their insurance coverage under the proposal and what impact it may have on premiums, as well as on the federal budget deficit — numbers many Republican senators said they need to see before making a final decision.

(Alice Li,Jorge Ribas,Libby Casey,Bastien Inzaurralde/The Washington Post)

It is unclear what a bill capable of attracting the 50 out of 52 Republicans needed for passage would look like — or whether such a compromise is possible. What is clear is that the bill McConnell released will need to change to survive.

“This current draft doesn’t get the job done,” Sen. Ted Cruz (R-Tex.) said. “But I believe we can get to yes.”

Cruz joined forces with three other Republicans — Sens. Rand Paul of Kentucky, Ron Johnson of Wisconsin and Mike Lee of Utah — to issue a statement saying that although they cannot support the bill as written, they are open to negotiating changes that could ultimately win their backing. Cruz, Lee and Paul are pushing for the bill to more fully repeal the ACA, while Johnson has worried that the legislation is being rushed.

On the other end of the GOP spectrum, Sen. Susan Collins (R-Maine) said she also has “concerns about some of the provisions.” She opposes blocking federal funding for Planned Parenthood, as the Senate bill would, and said she was unsettled by the changes to Medicaid that would result in long-term federal spending cuts to the program.

Sen. Dean Heller (R-Nev.), who is up for reelection in 2018 in a purple state that expanded Medicaid under the ACA, said he has “serious concerns” about the Medicaid provisions.

Like the bill that passed the House in May, the Senate measure would cut off expanded Medicaid funding for states — but at a more gradual rate, by phasing out the higher federal spending between 2020 and 2024. But it would enact deeper long-term cuts to the program, which provides health-care coverage for 74 million Americans.

Rick Pollack, president and chief executive of the American Hospital Association, said in a statement that the plan “moves in the opposite direction” in terms of providing health coverage and that “Medicaid cuts of this magnitude are unsustainable and will increase costs to individuals with private insurance.”

Which GOP senators have concerns with the health-care bill

In a nod to centrist senators, the Senate bill would preserve two of the ACA’s most popular provisions: Insurers could not deny coverage based on preexisting conditions, and children could stay on their parents’ plans until the age of 26 — though critics said people with past illnesses might not be able to afford plans under the revamped rules.

But the bill would allow states to use an existing ACA program, known as 1332, in which they can file for waivers from the Centers for Medicare and Medicaid Services that allow them to scale back the requirements for plans offered by insurers.

Some argued that the complaints about McConnell’s proposal — particularly from the GOP senators who came out quickly and forcefully against it — amounted to little more than posturing that would allow critics to eventually claim credit for reshaping the final version of the bill.

“If anyone actually believes Ted Cruz isn’t going to vote for final passage of this bill, well, I have some rainforest in Arizona to sell you,” John Weaver, a Republican strategist, wrote on Twitter.

Cruz, who is up for reelection in 2018, helped start a health-care working group that has been huddling for months. Allies have said that Cruz wants and needs to support a repeal bill, leading many to conclude that he will eventually come around.

The Senate bill would abolish the penalties for two of the ACA’s central mandates — that individuals must show proof of insurance when filing their taxes and that firms with 50 workers or more must provide health coverage — while providing less money for moderate- and low-income Americans buying insurance on the individual market.

Cruz said he wants to eliminate even more regulations so that insurers can offer cheap plans with bare-bones coverage. He also wants to allow people to buy plans across state lines, expand health savings accounts and cap the amount of damages that can be awarded in medical malpractice lawsuits.

McConnell introduced his draft text — which he spent weeks crafting with only a small circle of aides — in a private meeting with Republican senators Thursday morning before showing it to the public.

“Republicans believe we have a responsibility to act — and we are,” McConnell said on the Senate floor.

McConnell is privately threatening to bring the bill to a vote next week, even if he does not have the necessary votes, according to two Republicans in close contact with Senate GOP leadership who were granted anonymity to describe private conversations.

But that message may be more of an attempt to pressure Republicans to support the bill rather than an ultimatum, and some aides and outside observers speculated McConnell would pull the bill rather than have it go down in defeat. A McConnell spokeswoman declined to comment.

There is still a dispute over whether Senate rules will allow the bill to include language in McConnell’s draft that would deny Medicaid reimbursements for Planned Parenthood’s services for one year. Federal law already prevents taxpayer funding to pay for abortions, except to save the life of the mother or in the case of rape or incest. But some Republicans want to ban all federal funding for Planned Parenthood, which also provides health services such as birth control and preventive screening.

While the House legislation would peg federal insurance subsidies to consumers’ age, the Senate bill would factor in income as well, as the ACA does. But younger people would still get more generous subsidies than they do now, and the bill would allow insurers to charge older consumers based on a 5-to-1 ratio, rather than the current 3-to-1 ratio.

“It needs to look more like a repeal of Obamacare rather than that we’re keeping Obamacare,” Paul said. He expressed displeasure that GOP leaders had not done more to undo the insurance subsides created under Obamacare.

Some medical experts warned that while the adjustments to the tax credits in the Senate proposal are better than the House bill, they would probably still fall short of what is needed.

Sharad Lakhanpal, president of the American College of Rheumatology, said in a statement that they “do not go far enough in ensuring individuals living with rheumatic disease will be able to maintain their current level of coverage.”

The bill is being moved under arcane budget rules that allow it to be passed with a simple majority. McConnell has little margin for error in a chamber where Republicans hold a 52-to-48 advantage and Democrats are firmly united against the legislation.

Senate Democrats swiftly protested the bill Thursday, criticizing Republicans for crafting it under secretive conditions and asking for more time to debate and vet the measure. Minority Leader Charles E. Schumer (D-N.Y.) said Republicans were “turning truth upside down” with their promises of an open amendment process next week.

Obama, who has weighed in sparingly on public policy since leaving office, posted a scathing critique of the Senate bill Thursday on Facebook, urging voters from both parties to lobby senators to slow down and renegotiate the measure. “Simply put, if there’s a chance you might get sick, get old, or start a family — this bill will do you harm,” he wrote.

Senate Republican Conference Chairman John Thune (S.D.) made it clear that party leaders are well aware of the challenge they face in marshaling sufficient GOP votes for their proposal.

“Forty-eight. That’s not enough to pass,” Thune said, counting out the four GOP senators who declared their opposition in a joint statement.

But, he added, “we’re not voting yet.”

Paige Winfield Cunningham, Elise Viebeck, Amy Goldstein and David Weigel contributed to this report.