Health care will define the midterms. Donald Trump's move to gut Obamacare guarantees it. Trump is doing what Republicans say they want. But trying to gut Obamacare and its protections for people with pre-existing conditions will be a loser this fall.

Andy Slavitt and Nicholas Bagley | Opinion columnists

Donald Trump and the Republican Party just put America’s health care squarely on the November ballot. After a year of trying and failing to repeal the Affordable Care Act, the Trump administration, in cahoots with 20 conservative states, has asked the courts to strike down several pillars of the ACA — including its protections for Americans with pre-existing health conditions.

These protections are a guarantee to as many as 130 million Americans that no insurance company can deny them coverage just because they (or one of their family members) had a prior illness or medical problem.

This single provision has not only allowed millions of Americans to care for their families. It’s also given millions more the economic freedom to change jobs or to start businesses without fear that they’ll lose their health coverage.

Insurance protections for people with pre-existing conditions are wildly popular, supported by majorities of both Democrats and Republicans.

Trump himself has promised to preserve that part of the law. “It happens to be one of the strongest assets,” he told CBS’ 60 Minutes right after he was elected. In legal papers filed Thursday, however, his administration urged a Texas court to wipe these protections from the books.

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It is rare for an administration to refuse to defend a federal law. This case is even more remarkable because overturning the ACA would harm tens of millions of Americans. Instead of doing its duty, however, the administration sided with the conservative states that sued it. Hours before the government took this unusual step, three career Justice Department lawyers withdrew from the case — presumably in protest.

The administration’s logic is worth trying to follow, if only to see the lengths to which it’s willing to go to stop people from getting the care they need.

It’s all tied to the big tax reform package that the Republicans passed in December. The bill mainly slashed the tax rate for corporations and those with large estates. But it also removed the penalty for people who can afford to buy insurance but who choose not to — commonly known as the “individual mandate.”

When they eliminated the penalty, Republicans didn’t repeal the rest of the ACA. They didn’t have the votes to do that. Eliminating the mandate was the best they could do to claim political victory.

The administration is now arguing that when Republicans wiped out the mandate, they created a constitutional problem — one that requires invalidating other parts of the ACA, including the part protecting people with pre-existing conditions. As the administration sees it, those parts can't be "severed" from the mandate and must also be unconstitutional.

We can’t blame you if your reaction to that paragraph is "huh?” We have a fair amount of legal and health care experience directly related to this law, in the Justice Department and the Department of Health and Human Services. And that’s our reaction, too.

The logic is so tortured and the claims are so weak that the lawsuit is widely considered frivolous. Even a conservative ACA critic, Jonathan Adler, called it “absurd.”

Have a headache trying to follow this? Does it make you a tad depressed or anxious? Be careful. If the Trump administration has its way, insurers could soon deny you coverage for those pre-existing conditions. The same would be true for serious prior illnesses such as cancer, diabetes and heart disease. Women’s health care and maternity care are also at risk: If the administration prevails, it could cost women more than men to get coverage.

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What happens next? The Justice Department has asked the court to keep pre-existing protections in place through 2018 — conveniently after the midterms, so voters may not fully recognize on Election Day what Republicans have in store for them. Sixteen states and the District of Columbia have already stepped up to defend the law. The case could eventually wind its way to the Supreme Court, lending additional import to the president’s next appointment should a vacancy occur.

In the meantime, insurance companies, who have already raised rates by double digits this year due to Republican sabotage, now have cause to raise them further.

The midterm election politics appear very bad for congressional Republicans. Already, some are attempting to distance themselves from the administration’s actions. But they have only themselves to blame for the position they are in.

Recall that Republicans’ first choice both before and after Trump became president was a straight repeal of the ACA. The Trump administration is just following through on what most Republicans said they wanted from the beginning.

Congressional Republicans should be called on to explain how they have helped Americans to better care for their families. Democrats should now be able to challenge even Republicans who are individually popular under the premise that their party doesn’t deserve to continue as the uncontested majority in Congress. Only with a majority in the Senate, Democrats will also argue, can they assure that a conservative Supreme Court won’t play politics in a case like this one.

Nothing has defined the domestic agenda over the past 18 months like health care. It’s only fitting that it will define the election, too.

Andy Slavitt, board chair of United States of Care and a member of USA TODAY's Board of Contributors, is a former health care industry executive who ran the Affordable Care Act and the Centers for Medicare and Medicaid Services from 2015 to 2017. Nicholas Bagley is a law professor at the University of Michigan and a former Justice Department attorney. Follow them on Twitter at @ASlavitt and @nicholas_bagley.