Today is a historic day for the state.

Uninsured low-income Utahns across the state can begin signing up to receive health coverage under Medicaid starting April 1 — an achievement that was years in the making and promises an opportunity for as many as 90,000 residents to lead a healthier, longer and more prosperous life.

The landmark, however, may be short-lived.

Last week, the Trump administration filed a brief in federal court supporting a Texas judge’s ruling that the Affordable Care Act is unconstitutional and should be struck down.

“The Department of Justice has determined that the district court’s judgment should be affirmed,” three political appointees wrote in the 5th Circuit filing.

Utah is among the 20 Republican-led states suing to have the law invalidated which, seeing how Utah is now embracing big parts of the Affordable Care Act, puts Attorney General Sean Reyes in kind of a mess.

Even as Utah proceeds to expand Medicaid, Reyes’ office and his colleagues are trying to undo the entire Affordable Care Act. If they are successful, we would be back at square one, with Congress and the states having to rebuild a health care law.

“Because the final outcome of Utah’s ACA challenge is uncertain, it is probably not inappropriate for the Utah Legislature to move forward [with expansion] under the current law,” said Reyes’ chief of staff, Ric Cantrell.

The ACA lawsuit predated passage of Proposition 3, Cantrell said, and, in Reyes’ view, “States should always challenge federal overreach. That is our job.”

In the past, however, Reyes has seen his job somewhat differently: Defend Utah’s laws, no matter what, not to pick and choose.

“Once laws have been passed, in my mind, the die has been cast. The people have spoken,” Reyes said during his first re-election campaign in 2014.

That statement was in the context of his defense of Utah’s ban on same-sex marriage. But I pressed him on it at the time. Hypothetically, if the Legislature passed a law that was unconstitutional on its face and morally repugnant to him personally, would he absolutely defend that law all the way to the Supreme Court, if necessary?

“Yes, or until the people change the law.”

Well, guess what? The people of Utah, Reyes’ 3.1 million bosses, have done just that. They changed the law by passing Proposition 3.

Not only that, the Utah Legislature added its own stamp of approval when it passed a law watering down Proposition 3, but still expanding Medicaid to the 90,000 low-income Utahns. The Legislature also decided to enable another 30,000 or so Utahns to continue purchasing subsidized health plans through the ACA marketplace.

That leaves Reyes on his own now, fighting to undo the will of Utah voters, the Legislature and the governor by overturning the Affordable Care Act. And make no mistake, if the lawsuit is successful, all of it would go away.

The protections for 391,000 Utahns with pre-existing conditions, gone.

The provisions allowing young people to stay on their parents’ insurance until age 26, vanished.

The Medicaid expansion that will enable as many as 90,000 of Utah’s poorest individuals to get health care, poof.

“On one hand, Reyes and the state are suing to eliminate all aspects of the ACA, including expansion. On the other hand, they’re counting on an administration that supports Utah in that position to approve ACA-based Medicaid expansion,” said Matt Slonaker, executive director of the Utah Health Policy Project. “It doesn’t seem like good planning or strategy to seek the very thing you are trying to eliminate. Politics is getting in the way of good sense.”

Indeed, in Reyes’ own philosophy, it’s not his duty or even his right to use the office to put his own policy or political beliefs ahead of the will of voters and the Legislature.

“If you want to make policy … you run for the Legislature. If you want a veto power, you run for governor,” Reyes said during a 2014 debate. “If you’re running for attorney general, you better be ready to defend all of the laws whether you agree with them or not, or whether they’re politically convenient or not.”

There is, of course, a simple way to resolve this tension, and that is for Reyes to mark today’s historic enactment by withdrawing Utah from the ill-conceived Texas lawsuit. That way, Reyes can honor both his own view of the proper role of an attorney general and the will of the Utah voters who he is elected to represent and who have spoken loudly and clearly on this issue.

Correction: Monday, April 1, 8:12 a.m. • The story has been updated to correct the comment from Ric Cantrell, who said it was "not inappropriate" for expansion to proceed. An earlier version omitted the word "not."