Yet another last-ditch effort to tackle the nation's health-care system stalled within hours of its release by a bipartisan pair of senators Tuesday, with President Trump sending mixed signals and Republicans either declining to endorse the proposal or outright opposing it.

The week began on Capitol Hill with a renewed sense of urgency to craft legislation following Trump's decision last week to end key payments to health insurers that help millions of lower-income Americans afford coverage but that the president argued were illegal under the Affordable Care Act.

The compromise offered by Sens. Lamar Alexander (R-Tenn.) and Patty Murray (D-Wash.) on Tuesday proposes authorizing those payments for two years in exchange for granting states greater flexibility to regulate health coverage under the ACA. Those payments help offset deductibles and other out-of-pocket costs for low-income consumers who obtain insurance through the law; critics of Trump's decision said eliminating the subsidies would cause insurers to back out of marketplaces across the country.

The measure presented congressional Republicans with an uncomfortable choice between helping sustain coverage for many Americans and making good on a long-standing campaign promise — and paying the consequences — by allowing the ACA to falter.

Senate Republican leaders did not immediately endorse the proposal. Influential House Republicans panned the blueprint, and Trump offered conflicting reviews. The discord swiftly cast the plan's viability into serious doubt.

In an address at a Heritage Foundation dinner in Washington on Tuesday, Trump commended "the bipartisan work" of Alexander and Murray but suggested that a different kind of fix is needed.

"I continue to believe Congress must find a solution to the Obamacare mess instead of providing bailouts to insurance companies," Trump said.

Earlier in the day, at a joint news conference with the prime minister of Greece, Trump sounded positive notes about the plan. "Yes, we have been involved, and this is a short-term deal," Trump said. He said the proposal would "get us over this intermediate hump" and allow Republicans to later revisit efforts to aggressively undo the ACA.

In between those two appearances, the president tweeted: "Any increase in ObamaCare premiums is the fault of the Democrats for giving us a 'product' that never had a chance of working."

Trump stopped the CSR payments last week, arguing that the subsidies were illegal because they were not explicitly authorized under the ACA, and he instructed Congress to decide whether to appropriate the funding.

"None of our guys voted for Obamacare," Rep. Tom Cole (R-Okla.), a close ally of House GOP leadership, said in an interview. "They're not very interested in sustaining it."

A leading House conservative was outright hostile to the new bipartisan plan. "The GOP should focus on repealing & replacing Obamacare, not trying to save it. This bailout is unacceptable," said Rep. Mark Walker (R-N.C.) in a statement posted on Twitter. Walker is the chairman of the influential Republican Study Committee.

Senate Republican leaders were less than enthusiastic.

"We haven't had a chance to think about the way forward yet," said Senate Majority Leader Mitch McConnell (R-Ky.) at his weekly news conference, minutes after Alexander announced the deal about 20 feet away, outside a Republican policy luncheon.

[States scramble for solutions for insurers that were counting on Obamacare payments]

Alexander said the deal he struck with Murray would extend CSR payments for two years and provide states "meaningful flexibility" under the ACA, allowing them to make changes to insurance offerings as long as the plans had "comparable affordability," which is a slightly looser definition than the existing one.

In an interview, Senate Minority Leader Charles E. Schumer (D-N.Y.) said both parties made concessions to produce a deal that would "stabilize the Affordable Care Act and undo a good amount of the sabotage that we've seen in recent days."

"Each side had to give some, but that's what this is all about," Schumer added.

The framework would also allow insurers to offer catastrophic insurance plans to consumers aged 30 and older on ACA exchanges, while maintaining a single risk pool. It would shorten the time period for federal review of state waiver applications, expedite review for states in emergency circumstances and those with waiver proposals that have already been approved for other states, and allow governors to approve state waiver applications rather than requiring state legislative approval.

Alexander emphasized that the legislation would not allow states to change the essential benefits insurers are now required to offer individuals and small businesses under the ACA, or let insurers discriminate against consumers with preexisting conditions. "This takes care of the next two years," the senator said, standing off to the side as other GOP leaders stood before television cameras talking primarily about tax legislation. "After that we can have a full-fledged debate on where we go long-term on health care."

Trump's decision to halt CSR payments last Thursday came a week after he had called ­Schumer to ask him to "work together on a bipartisan solution to health care," in the senator's words, and had empowered Alexander to negotiate with Murray.

Schumer said that he realizes Trump may push later on for repealing the ACA outright, "and we will fight him tooth and nail." But he added, "In the short run, stability is in his interest, because otherwise its lands at his doorstep."

Still, it remains unclear how Trump will choose to speak about the bipartisan deal in the coming weeks and days, and whether recalcitrant conservatives will come along.

The first test will come in the Senate, where lingering hard feelings from the failed attempts to repeal and replace the ACA remain. Senate GOP leaders have moved on to tax cuts, their next big legislative undertaking.

After Trump voiced his support for the health-care compromise, Sen. John Cornyn (R-Tex.), McConnell's top lieutenant, was unwilling to commit to it.

"I think Sen. Alexander's done good work. And to me, it really depends on a few things," said Cornyn, wondering aloud whether the proposal is "compatible" with the GOP's larger repeal-and-replace goal.

Earlier Tuesday, Sen. Lindsey O. Graham (R-S.C.), who was golfing with Trump on Saturday when the president discussed the prospect of negotiations on the phone with Alexander, said that even if a deal is struck, it may not be enough of an overhaul to satisfy core Republican voters.

"That will be his challenge, how much is enough? I can't support the payments until you get some reform, but I realize that for the base, it's going to be about not keeping Obamacare in place," Graham told reporters.

In advance of the deal's announcement, many Republican senators were already distancing themselves from the emerging plan.

"I don't know. I'm not sure what the Senate should do," said Sen. Orrin G. Hatch (R-Utah) Tuesday morning.

In the House, which passed an ACA repeal bill, there appeared to be even less appetite for a bill that bolsters an element of the law that they have pilloried for seven years without more forcefully rolling back other parts of it.

"This is like we have to fix the Senate's failure," said Cole. Using a football analogy, he blamed Senate Republicans for fumbling the ball on the one-yard line.

In the eyes of Cole and other leading Republicans, the party's congressional majorities were put at risk by the unsuccessful repeal push. With Trump's former chief strategist Stephen K. Bannon already threatening primary challenges against senators up in 2018, some fear that asking lawmakers to reinforce the bill they tried to undo is simply not a defensible position.

On the other hand, doing nothing is also likely to spur criticism of the Republicans.

As senators announced their agreement, a new analysis emerged Tuesday showing the large stakes for insurers in the short term if the cost-sharing payments are not restored. By the end of 2017, health plans will lose more than $1 billion nationwide, according to the analysis by Avalere Health, a Washington-based consulting firm.

Both state and industry officials welcomed the prospect of a possible deal on the subsidies, but they also warned that it could come too late given that the 45-day open enrollment period for the ACA begins Nov. 1.

The timing — just two weeks before the start of the fifth enrollment season for ACA coverage — could mean havoc back in states, where some insurance regulators already are reeling from Trump's decision to stop funding CSRs.

"It is better for consumers to have CSRs funded, but the timing is so short I am concerned," said Tennessee Insurance Commissioner Julie Mix McPeak, the incoming president of the National Association of Insurance Commissioners. If the deal becomes law, she said, insurers would be able to lower their rates in ACA marketplaces, "but I don't know that we have time to do that before open enrollment."

It appears likely that the vast majority of Senate Democrats will back the measure: Murray received a round of applause from her colleagues when she announced the details of the agreement in their weekly caucus lunch, according to participants, and no one expressed dissent.

Still, Democrats said that they wanted to read the details of the bill. Sen. Chris Murphy (D-Conn.) said that the idea of expanding the availability of catastrophic plans on the ACA market and making state waivers easier to obtain "is not insignificant."

Even if Democrats embrace the plan in large numbers, Murphy said, Republicans could ultimately block its passage.

"It is not a done deal that this agreement reached by Senators Alexander and Murray will ever become law," he said.

John Wagner contributed to this report.

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