A relatively small provision included in the Tax Cuts and Jobs Act, passed in December 2017, gives President Trump the ability to achieve what his party has failed to accomplish.

After more than eight years of promising to repeal the Affordable Care Act (ACA), the Republican-led Congress has yet to pass legislation that would replace Obamacare, which has forced millions of Americans to lose their doctors, caused dramatic increases in health insurance premiums and deductibles, and pushed millions more into Medicaid.

However, a relatively small provision included in the Tax Cuts and Jobs Act, passed in December 2017, gives President Trump the ability to achieve what his party has failed to accomplish — ending the disastrous Obamacare program — and without the approval of Congress.

Following the passage of the ACA, the health-care law faced numerous legal challenges, culminating in a controversial 5–4 decision by the Supreme Court in 2012 to uphold the ACA, with Chief Justice John Roberts delivering the deciding vote. In Roberts’ opinion, he reasoned the provision requiring all Americans to purchase “qualifying” health insurance or else pay a fine was constitutional on the basis that the “fine” is actually a tax. Since Congress has the power to impose taxes, Roberts determined the ACA constitutional, breaking with other conservative justices as well as the court’s liberal justices, who argued the individual mandate is constitutional because Congress has the authority to regulate interstate commerce.

Roberts’ view that the individual mandate amounts to a tax, despite the language of the bill and repeated denials by the Obama administration that the ACA raises taxes, has been the subject of much criticism, but it could now serve as the basis for eliminating the entire law, thanks in large part to the tax reform bill Congress passed in December.

On January 1, 2019, the Tax Cuts and Jobs Act eliminates the penalty on those who do not purchase qualifying health insurance plans. The fine is currently $695 per adult, up to a family maximum of $2,085, or 2.5 percent of income, whichever is greater. Without the penalty, the Affordable Care Act’s individual mandate can no longer reasonably be considered a tax, and thus the entire basis upon which Roberts built his defense of the law has evaporated.

Further, it’s unlikely the Supreme Court will determine the mandate is unconstitutional while leaving the remainder of the law in place. The four justices who dissented from Roberts’ 2012 decision determined the ACA’s key provisions could not survive if the individual mandate is determined to be unconstitutional. (Roberts never addressed that question in his opinion.)

The Supreme Court has used a two-part test to determine whether a single provision in a law that has been determined to be unconstitutional can render the entire law unconstitutional. As former Justice Antonin Scalia noted in his dissent in the 2012 case upholding Obamacare’s constitutionality, the first part is “whether the now truncated statute will operate in the manner Congress intended. If not, the remaining provisions must be invalidated.”

“Second, even if the remaining provisions can operate as Congress designed them to operate,” Scalia continued, “the Court must determine if Congress would have enacted them standing alone and without the unconstitutional portion. If Congress would not, those provisions, too, must be invalidated.”

Because Congress reduced the individual mandate to $0, it would be very difficult to argue the remaining aspects of the Affordable Care Act would not operate as intended if the mandate is ruled unconstitutional. However, it would be far easier to show that Congress, which called the individual mandate “essential” to the law’s operation when it was passed, would have enacted the remaining provisions in Obamacare absent the individual mandate.

We’re not alone in our assessment of the Affordable Care Act. Twenty states and several other plaintiffs filed on April 23 a lawsuit in the U.S. District Court for the Northern District of Texas alleging Obamacare is no longer constitutional for many of the same reasons outlined above. But there’s no need for the Trump administration to wait for courts to resolve this dispute. As America’s chief executive branch officer, Trump can choose not to administer the ACA’s provisions due to its unconstitutionality by simply issuing an executive order in which he directs federal agencies not to enforce the law once the penalty is eliminated in 2019.

An even better solution would be for President Trump to publicly announce his administration plans to end the Affordable Care Act in 2019 and that Congress must reform the law now or else risk the entire Obamacare system collapsing in less than a year. This threat would likely be immune from any legal challenges from states seeking to keep Obamacare in place, because nothing legally binding would have been issued by the Trump administration, and it might provide the circumstances needed to compel Congress to finally pass new health-care legislation.

In a single tweet, President Trump might be able to do what his Republican counterparts in Congress have repeatedly failed to accomplish, opening the possibility to much-needed reform of America’s failing health insurance system.