What will happen with healthcare policy under President Trump ... or ... Clinton?

The November elections surely won't end the nonstop, eight-year political war over the shape of the U.S. healthcare system. But the ballot results likely will determine whether the changes driven by the Affordable Care Act continue in the same direction or the system returns to its less-regulated, pre-ACA contours.

Heading into this week's Democratic National Convention, Hillary Clinton has promised to preserve and expand the ACA's coverage expansions and delivery system reforms. Donald Trump, who accepted the Republican nomination last week, says he wants to repeal them, without offering much detail about what he would put in their place. The fate of the victor's proposals, however, will depend heavily on the partisan makeup of Congress.

The clearest scenario is if Trump wins and his party retains control of both the House and the Senate, which would enable conservatives to repeal or roll back the ACA and implement at least some of the proposals outlined in the GOP party platform and the recent House Republican leadership white paper on healthcare. But there are divisions even among conservatives over issues such as Medicare restructuring and how to help Americans afford health insurance. And Senate Democrats almost certainly would use their filibuster power to block major ACA changes.

If Clinton wins and Democrats take control of both the Senate and the House—which is considered unlikely—she might be able to push through proposals such as increasing funding for federally qualified community health centers. But Senate Republicans also could use the filibuster to foil her. In the more likely scenario of a Democratic-controlled Senate and a GOP-controlled House, it's not clear how much Clinton could achieve through the legislative process.

That's why some observers predict that a President Trump or a President Clinton would have to use executive powers to put their healthcare policies in place. One possible tool is Section 1332 of the ACA, which lets the federal government grant waivers to states to opt out of the ACA's exchanges and achieve coverage and cost control goals via innovative models.

But the administrative approach carries political and legal risks. The Obama administration has faced a number of court setbacks and infuriated congressional Republicans with its administrative end runs.

Here are some questions and speculations about how the election could affect key health policies:

The law will survive and undergo repairs if Clinton wins, becoming more firmly entrenched by the end of her term.

She has promised to improve the functioning of the ACA markets by offering additional subsidies to consumers to make premiums, out-of-pocket costs and prescription drug costs more affordable. She also wants to boost exchange enrollment through aggressive outreach, tougher cost controls and continued delivery system reforms. “The combination of these steps should increase enrollment, stabilize the marketplace, reduce premiums, and convince more plans to enter the market because there will be more and healthier customers,” said Chris Jennings, an outside health policy adviser to the Clinton campaign.

This month, she updated her healthcare platform to more strongly embrace a public plan option in the exchanges. But there are doubts about whether she seriously intends to pursue the controversial public option approach if she's elected.

“I'm not sure (the public option) would be in her 100-day agenda or in her two-year agenda,” said Jim Manley, a former top aide to Sens. Harry Reid and Ted Kennedy who worked on drafting the ACA. Even if the Democrats win control of the Senate in November, he noted, it would take 60 votes to pass a public option measure and other ACA changes, and that's a high hurdle.

Douglas Holtz-Eakin, an adviser to John McCain's presidential campaign in 2008 and former director of the Congressional Budget Office, said Clinton's agenda for improving and expanding the ACA would be dead on arrival in Congress because there's no money to fund it and because Republicans are fiercely against it.

So how could Clinton implement any of her ACA fixes? She would look at administrative as well as legislative options, Jennings said. “She'll work very aggressively to go as far as she can to ensure Americans in the exchanges have a viable choice of health plans.”

Under Trump, the ACA probably would be shrunk rather than abolished and would receive a new name. It's widely expected that Trump would hand off the health policy portfolio to House Speaker Paul Ryan, whose recent House leadership white paper is seen by conservative wonks as the blueprint for a Republican administration's policy. Republicans likely won't completely repeal the law despite their long-standing promise to do so. The political backlash from suddenly ending ACA coverage for an estimated 20 million Americans would be too great. Perhaps even more important, they won't be able to get 60 votes in the Senate for repeal.

Still, Trump and congressional Republicans would try to end the individual and employer mandates, eliminate ACA insurance reforms such as minimum essential benefit packages, pare back and restructure the premium subsidies, and junk the CMS Innovation Center and the Medicare Independent Payment Advisory Board, Holtz-Eakin said.

Experts say those measures would largely unravel the ACA system and could lead to millions of people losing coverage.

It's not clear whether or how a Trump administration would provide subsidies to help people buy or keep coverage. The House Republican leaders' plan proposed refundable tax credits for individuals without access to employer-based or public coverage. But the Trump campaign's seven-point healthcare proposal and the GOP health policy agenda don't mention any subsidy mechanism. Another issue is that if they moved to repeal the ACA and its hundreds of billions in revenue, Republicans would have no way to fund subsidies for the uninsured, noted John Goodman, a veteran Republican health policy expert.

House GOP leaders have proposed taxing employer health benefits to provide revenue for subsidies and help control overall healthcare spending. But it's not clear whether Trump would embrace such a widely unpopular measure. The bottom line, many observers predict, is that Trump would whittle away at the ACA but wouldn't chop it down.

It won't if Clinton wins. But she will push for a continued shift to value-based reimbursement models such as bundled payment and accountable care. And to address affordability, she might try to pass her proposal to let people 55 and older voluntarily buy into Medicare, though Republicans would strongly oppose it.

On the other hand, there is the potential for changes to improve Medicare benefits and care coordination and reduce costs for patients with chronic conditions, which have bipartisan support. There's also an outside chance for a deal on GOP-backed reforms merging Medicare Parts A and B, capping out-of-pocket costs for seniors and potentially saving the program money by requiring deductible payments.

If Trump wins, Ryan and congressional Republicans will press hard to transform Medicare into a so-called premium support program, in which the government makes fixed per-capita contributions and beneficiaries use those payments to get their care from either traditional Medicare or private plans. A move away from defined benefits would potentially expose seniors to higher out-of-pocket costs. The GOP platform includes that proposal, even though Trump repeatedly promised in the primaries to leave Medicare unchanged.

Holtz-Eakin suggested that a Trump administration might try to nudge Medicare toward a premium-support model by making the privatized Medicare Advantage program more of a competitive bidding system. “They could do it in a sequential way and (eventually) get rid of CMS price-fixing entirely,” he said. To win Democratic support for this, he added, the Republicans might agree to expand the bundled-payment model within traditional Medicare.

Clinton says she will ask Congress to extend the ACA's enhanced, 100% federal matching rate for covering low-income adults to states that have not yet expanded Medicaid. That would incentivize the 19 non-expansion states to extend coverage. But she would need a Democratic-controlled Congress to pass it.

Even so, it's expected that more Republican-led states would accept the expansion to help their hospitals and their budget pictures once it's clear that the ACA is here to stay under a Democratic president. Florida, Oklahoma, Tennessee, Utah and Wyoming are among the states where key GOP state leaders have backed expansion.

In contrast, Trump and GOP congressional leaders want to convert Medicaid into a system of capped federal contributions to the states and give state leaders enormous freedom to set eligibility, benefits and program structure. Democrats, healthcare providers, and even many state officials oppose such a change, fearing it would slash funding, reduce provider payments, and leave lots of low-income people without healthcare.

The House Republican leadership plan, which calls for repealing the ACA and its Medicaid expansion, would let states roll back their coverage extensions to “able-bodied” adults. At the same time, conservative experts argue that giving states more flexibility under the block-grant approach, such as letting them set work requirements and trim benefits, would enable them to cover this population more cost-effectively.

Holtz-Eakin said there could be a bipartisan Medicaid deal between a President Clinton and a GOP-controlled Congress, with Clinton getting expansion in all 50 states in return for giving state officials greater leeway in program design. It might even involve giving each state a single pot of money to cover both the Medicaid and exchange populations. “There's a trade in there somewhere,” he said.

Clinton wants to cap Americans' out-of-pocket costs for prescription drugs, let Medicare negotiate drug prices, and allow consumers to buy lower-cost drugs from foreign countries with approved safety standards. But those measures would face all-out resistance from the powerful pharmaceutical industry.

Trump also has called for letting Medicare negotiate prices. But GOP congressional leaders reject that, preferring to focus on reforms to speed Food and Drug Administration approvals for new drugs and devices that they say will reduce costs. Despite that stance, some conservative health policy experts have said a Trump administration would face mounting public pressure to address the drug cost issue.

John Rother, a veteran healthcare lobbyist who heads the Campaign for Sustainable Rx Pricing, said the proposals by Clinton and Trump to have Medicare negotiate drug prices are not politically viable and that it would be better to focus on achievable goals such as increasing price transparency and competition. Medicare negotiating drug prices “is not going to happen in Congress as I know it,” he said.