Republican regulars are melting down in fear that Donald Trump will lead the party to disaster in November. Let’s check that assumption.

First: This general election is going to be the ugliest in US history — no matter whom the GOP nominates, because that’s Hillary Clinton’s plan.

Once she’s ground Bernie Sanders to dust, Clinton will reactivate her Goldman Sachs ATM card, hoover up a billion or so from Wall Street, Hollywood, Silicon Valley, etc. — and prep the mother of all attack-ad blitzes.

It’s her only option: She’s too known a quantity to improve her image. She can’t pull off Barack Obama’s 2008 “hope and change” approach, only his 2012 “win by destroying your opponent” tack.

In 2012, Obama won 3.5 million fewer votes than in his first run. But he focused his efforts on getting his people out — and suppressing the pro-Romney vote with week after week of vicious lies and smears.

Romney couldn’t answer with his own ads — his campaign was broke. For weeks, all he could do was raise cash.

For the record, Marco Rubio would be in the same spot. Paul Krugman this week already sketched out the Clinton attacks on him: He wants Mitt Romney to pay ZERO taxes, and he’s a warmonger just like W. They’ll find or create personal dirt, too — as they will with any GOP nominee.

Trump won’t be left mute. He can write a $1 billion check and get right back in the fight. (Note to The Donald: Real estate assets aren’t that liquid. I hope you’re freeing up cash now.)

Of course, even Trump will be taken aback by the venom that’s about to come his way. It’ll make the primary look like a knitting circle, and Megyn Kelly seem as sweet as Melania.

He’s spent a lifetime cutting real estate deals. Decades of enemies will dish. Team Hillary will ghostwrite the 20-part New York Times series on all the little people he’s supposedly screwed over. People from his grade-school classes will say he was a bully even then.

Still, he’s also spent a lifetime in the New York media market. He’s already proven he hits back hard — and that’s the only answer that works.

Look: He’s already shut up the Clintons. She started calling him anti-woman, and he went right to the rape card — citing charges never disproven, and the fact that Hillary helped silence Bill’s accusers.

And Clinton’s attacks may not even take. For Trump’s base, the fact that he’s a jerk is a plus — because he’s their jerk. He’ll do what it takes to deliver for them.

Can he get the regular GOP base to come out and vote for him? Well, that’s the easiest trick in the book.

They came out for John McCain in ’08, and Mitt Romney in ’12, despite the years each had spent far off the reservation.

And he’ll be running against Hillary Clinton — who has personified evil for Republicans for more than two decades now.

With control of the Supreme Court on the line. It’ll be easy for The Donald to assure the base here: I loved Scalia — what a class act. Maybe I’d appoint his son — what a gorgeous service that was. Why can’t we put a priest on the court? By the way, the Catholics love me . . . Anyway, we’ll practically clone Scalia, and maybe that Alito guy too. I love Italians — such a warm people. Clarence Thomas — what a mensch. They tried the same crap with him that they’re trying with me. A great American.

Nor does the base much mind Trump’s major deviations from GOP orthodoxy: It’s the big donors who get hot and bothered on trade and immigration, but they have almost no votes, just money.

Money that Trump doesn’t need.

Head to head with Clinton? Sure, he talks in “word salad,” but he always gets his point across. She’s stiff and a compulsive liar — worse: She’s a bad compulsive liar.

Big picture: Since the first George Bush won in 1988, no Republican’s broken 50 percent of the vote except W’s 51 percent in 2004 — against John Kerry, one of the worst candidates ever.

Trump looks to have locked up the working-class voters the GOP needs to smash through the 50-yard line. He needs the Republican base to come out and vote for him, too — but he doesn’t have to make them love him, or even like him.

They just have to hate Hillary more — when she’s running as Barack Obama’s heir.

Looks like pretty good odds to me.