Virginia Democratic gubernatorial candidates Lt. Gov. Ralph Northam, left, and former congressman Tom Perriello shake hands after a debate at a Union hall in Richmond on May 9. (Steve Helber/Associated Press)

Amid the whirlwind of hysteria over President Trump’s decision to withdraw from the Paris climate agreement came a genuine revelation: Democrats and progressives embracing an idea they once held in contempt: federalism.

And it’s all thanks to Donald Trump.

Gov. Terry McAuliffe (D), who signed an executive order in mid-May directing the state’s Department of Environmental Quality “to begin the process of establishing regulations in Virginia that will reduce carbon emissions from power plants,” issued a statement Thursday in which he said he hoped his order would spur other states to “join Virginia in showing Washington the way forward on this critical issue for our nation and our world.”

Lieutenant Gov. Ralph Northam (D), a candidate for governor, echoed McAuliffe’s line, saying he is “committed to continuing that process” McAuliffe set in motion and would be out there “fighting the reckless actions of the Trump administration at every turn.”

But for Northam’s challenger, this doesn’t go far enough.

In a video posted to his Twitter feed, Democratic gubernatorial candidate Tom Perriello picked up the threads of McAuliffe’s statement, saying that “at the state level, we will step up and do our part to lead on addressing climate change and making sure that our coastline here in Virginia and all of our clean air and clean water is protected.”

But Perriello went much further, promising that if he becomes Virginia’s next governor, he would “push for Virginia to join” an “alliance of states of states committed to saving our planet.”

The alliance in question, led by New York Gov. Andrew Cuomo, California Gov. Jerry Brown and Washington Gov. Jay Inslee, all Democrats, says it is “committed to achieving the U.S. goal of reducing emissions 26-28 percent from 2005 levels and meeting or exceeding the targets of the federal Clean Power Plan.”

States banding together to thwart an unreasonable federal government action?

That’s not new; that’s federalism.

And if it all sounds very familiar, it should: Ken Cuccinelli blazed the federalism trail during his time as Virginia’s attorney general.

In a 2011 speech to Hillsdale College’s Kirby Center for Constitutional Studies and Citizenship, Cuccinelli discussed the number of lawsuits states had filed against the federal government — over Environmental Protection Agency regulations, the Affordable Care Act and others — and how it all represented “pushback” against a federal government that had overstepped “its constitutional bounds.”

Of his legal challenges to the federal government, Cuccinelli said: “When I ran for attorney general of Virginia, I said that if the federal government crossed certain lines, I would challenge it.”

Cuccinelli added that with the support of “fellow Virginians and the American people, we have planted our flag and we are taking a stand. And if we are successful, future generations of Americans will have a chance to enjoy the liberty that has made America the envy of the world.”

He made an explicit case for federalism in standing up to EPA regulations on greenhouse gas emissions. Perriello does not use the word but comes to similar conclusions for opposite ends.

In the topsy-turvy world of politics, Cuccinelli’s fight for individual liberty has become Perriello’s fight for the planet.

The tea party meets the resistance — and both find themselves marching under the banner of federalism.

Before Virginia’s elections are finished in November, we might even see a Democratic candidate talking about the rights of sovereign states to challenge federal over reach.

And all because of Donald Trump.