The presidential candidates' views on the Affordable Care Act are well-known. Hillary Clinton would keep it but fix it. Donald Trump would repeal it and replace it with a patchwork of initiatives aimed at lowering costs and regulations. But whether either candidate can deliver on their campaign promises if elected is a lot less certain.

Remember, we're dealing with three highly inefficient bureaucracies--the government, insurance companies, and the health care system. Expecting anything to happen fast is a setup for disappointment. "Even with a change in leadership and congressional makeup, you can't unravel what's been done very quickly," says Katy Stowers, an attorney with FirstPerson, a benefits adviser in Indianapolis. "Making any plans based on expected changes in the political climate is foolhardy."

But how likely are we to see any changes at all? Here are some of the candidates' key health care proposals, and their chances of success.

Trump: Repeal it!

Earlier this week, Trump boasted that would "ask Congress to convene a special session so we can repeal and replace" Obamacare, adding, "We will do it very, very quickly." First of all, Congress will already be in session when the next president takes office, so calling a "special session" isn't necessary. Beyond that, repealing the health care law would require Republican control of the White House, the Senate, and the House of Representatives. That's why Republicans, despite voting to repeal more than 60 times, have been unable to do so thus far. Further, unless Republicans have a 60-vote majority in the Senate, which seems very unlikely, Democrats could filibuster and block a full repeal bill from moving forward.

Republicans would still have one potential path forward, though: an obscure legislative process called budget reconciliation. The process could permit expedited approval of changes to parts of the health care law that have a direct, measurable effect on federal spending, to bring the laws in line--or reconcile them--with the annual budget plan approved by Congress. Reconciliation bills can't be filibustered, so Republicans wouldn't need a 60-vote senate majority to proceed, just a simple majority. (All Senate Democrats have vowed to fight repeal.) While it wouldn't technically be a complete repeal of the law--because many of the ACA's provisions don't have a significant budget impact--a well-crafted reconciliation bill could effectively dismantle Obamacare as we know it.

Republicans in the House and Senate have already succeeded in passing a reconciliation bill that would have undone key components of the ACA, such as premium subsidies for people with moderate incomes, expansion of Medicaid to cover more people, and individual and employer coverage mandates. The Congressional Budget Office determined that dropping these provisions would reduce federal deficits by $913 billion through 2025. It also would have caused about 22 million American to lose insurance coverage by 2018. When the bill hit President Obama's desk in February, he vetoed it. A President Trump, presumably, would have signed it.

Trump: Let insurers cross state lines

A key part of Trump's "replacement" plan is allowing insurers to sell health plans across state lines. It's an old idea--a bill to allow interstate insurance sales was introduced in Congress in 2005. While it didn't pass, it has become part of the platform of every Republican presidential nominee since.

Proponents argue that states with stricter coverage requirements on health insurance plans are artificially inflating premiums and making insurance unaffordable for residents. Allowing health plans registered in states with fewer requirements to be sold in more heavily regulated states would allow consumers to find plans more in line with their health needs and budget. Insurance companies would be able to base themselves in states with the most lenient regulations, avoiding those whose mandates they don't like (much the way corporations overwhelmingly register in business-friendly Delaware).

Opponents of this proposal believe it would mainly benefit young and healthy people in states with lots of health-insurance mandates. Older, less healthy people would be worse off. Right now, in addition to state regulations, the ACA sets up federal standards for what plans must cover, and prohibits discrimination in rates based on preexisting conditions. If these national standards were repealed, insurers based in states with lenient coverage rules would have few incentives to offer affordable, comprehensive plans to people in poor health.

And the truth is, insurance companies aren't really interested in supporting national plans, which require cobbling together networks of doctors and hospitals in unfamiliar markets. Six states have passed laws to encourage cross-border insurance sales, but a Georgetown University analysis found that they failed to draw new plans into their markets or reduce costs.

Trump: Health savings accounts

The other big idea touted by Trump is letting people use health savings accounts, or HSAs. Of course, many people already do so--according to research firm Devenir, more than 16 million Americans have HSAs, which allow you to set aside pre-tax income toward anticipated health costs in an interest-bearing account. The money is only taxed if you use the money for non-health spending, and unused funds accumulate over time and can be taken from job to job. Right now, HSAs are available only to people with high-deductible health plans. Trump hasn't proposed specific changes to current HSA rules, so this proposal isn't really offering anything new.

Clinton: Get co-pays, premiums, and deductibles down

The Democratic nominee has promised additional public subsidies to lower premiums and out-of-pocket costs for everyone, not just those earning incomes of less than 400 percent of the federal poverty level who currently qualify. Under her proposal, people who buy insurance in a public exchange would have to pay more than 8.5 percent of their income for health coverage, down from 9.66 percent this year.

Clinton also would offer a tax credit for families whose out-of-pocket medical costs exceed 5 percent of their income. She would increase outreach--and possibly penalties--to get more people, especially young, healthy ones, to buy health coverage. (A healthier pool of insured means lower premiums for all, in theory.) And she has said she would push for a "public option," or a government-run health plan, to increase competition.

Even if the Democrats win control of the Senate, it would take 60 votes to pass almost any changes to the ACA itself. It's not clear that Democrats will hit that number after next week's elections. It might be possible to sneak in a public option through state exchanges, though, using "innovation waivers" built into the ACA, which wouldn't require additional legislation. The public option is highly controversial, however, and not something a President Clinton would likely prioritize at the risk of burning political capital early.

Both candidates: Tackle prescription drug costs

Clinton proposes to do this by denying drug makers tax breaks for direct-to-consumer advertising, offering them only for money actually invested in R&D. She would encourage competition to get more generic drugs on the market, and follow the example of states like California and Maine by setting a monthly limit of $250 on out-of-pocket prescription drug costs for individuals.

Both candidates have called for allowing Americans to import drugs from abroad and for letting Medicare negotiate drug prices directly with pharmaceutical companies, rather than through a network of benefits administrators. These measures would face strong opposition from the powerful pharmaceutical industry lobby, though, which has many friends on both sides of the aisle.