Senate Democrats are treating President Trump’s selection of Judge Brett Kavanaugh for the Supreme Court as the end of civilization. And that’s not much of an exaggeration.

“Judge Brett Kavanaugh represents a direct and fundamental threat to the promise of equality” and to “the health care of hundreds of millions of Americans,” said Sen. Kamala Harris (D-Calif.), a top contender for her party’s 2020 presidential nomination.

So much for a fair and honest evaluation — which they aren’t even pretending to make before declaring their opposition. Then again, the over-the-top, patently ridiculous rhetoric proves that Democrats see this as nothing but a political game.

It’s likely to backfire, though: Lacking a Senate majority, the Dems will have to peel off one or two Republicans to stop Kavanaugh.

But one of their prime targets, Sen. Susan Collins of Maine, let it be known Tuesday that she’s not buying the argument that the judge is unfit for the high court.

“When you look at the credentials that Judge Kavanaugh brings to the job,” she said, “it’ll be very difficult for anyone to argue that he’s not qualified for the job.”

Indeed, he’s more than just qualified. In his 12 years on the federal appeals bench, he’s built an exemplary record that’s left a decided impact on the law: The Supreme Court has fully adopted the logic behind 11 of his decisions in its own rulings.

And while that record is reliably conservative, he’s far from the “hard right” extremist described by, among others, New York’s own Chuck Schumer. The Senate minority leader vows to fight Kavanaugh “with everything I’ve got.”

“Everything” includes breaking with 25 years of precedent to press Kavanaugh to say how he’d vote on specific cases.

This, notwithstanding the warning by Ruth Bader Ginsburg that doing so shows “disdain for the entire judicial process.” When “Notorious RBG” said that at her 1993 confirmation hearing, Democrats cheered.

Now, however, this is all about appeasing the party’s increasingly extreme base, which has long looked to the federal courts as a de facto liberal legislature.

Justice-designate Kavanaugh, on the other hand, would ensure faithful adherence to the Constitution. No wonder Schumer & Co. are terrified.