President-elect Donald Trump stated repeatedly on the campaign trail that he fully intends to repeal and replace Obamacare, or the Affordable Care Act (ACA). The Department of Health and Human Services estimates that 20 million people now have health insurance due to the Act. When will your insurance under Obamacare end with Trump in the White House? That all depends on how far Trump takes his effort to dismantle the legislation.

A full-scale repeal of the law would be difficult; it would require the Senate to have 60 votes to overcome a likely filibuster from pro-Obamacare Democrats, NPR reported. Heading into 2017, Republicans maintain only a very slight majority in the Senate.

But there are several ways in which Trump could effectively shut down key aspects of the legislation unilaterally and immediately, effectively though not officially undoing it. The most effective swipe Trump could take at Obamacare would be to drop the current administration's appeal of a lawsuit entitled House v. Burwell. That suit was brought by House Republicans who charged that Obamacare's reimbursements to insurers are made with money that hasn't been appropriated by Congress, which they claim is unconstitutional.

A Federal District Court ruled in favor of the Republicans, but isn't enforcing it until a higher court rules on the appeal. If Trump dropped the appeal, enforcement would kick in. Why would this be catastrophic for Obamacare? Those reimbursements go to insurers who give big discounts to the working poor, accounting for more than half of Obamacare recipients. The discounted rates are required by the ACA; without reimbursements, insurers would be very likely to simply drop out of the exchange.

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The move to drop the appeal could make a real fast impact on Obamacare, but the question we have to ask is: Would Trump endeavor such a move without first having something else in place, and without providing for a transition period for those currently insured under the ACA (something Vice President-elect Mike Pence promised would occur)? Trump has advanced some proposals for replacing Obamacare throughout his campaign — increasing intrastate competition, encouraging personal health care savings with tax-free accounts, and allowing people to deduct premiums from their income taxes being primary among them.

But these things take time to put into play, and they might not be adequate to replace insurance for those who would lose their Obamacare coverage. As The New York Times reported, insurers don't tend to be keen on intrastate competition because of the cost of setting up contracts with doctors and hospitals out of state. And changes to the tax code must go through Congress.

Obamacare is likely to fundamentally change under a Trump administration. How much and how quickly depends on which route he pursues to dismantle it, and, hopefully, how quickly he implements measures to replace that insurance for the many who will lose their coverage.