Don’t blame President Donald Trump for the setback Republicans are facing this November.

Ahead of next year’s congressional midterms , the first big test of the GOP’s strength since Trump returned to office comes this fall in New Jersey and Virginia.

While Republicans always expect an uphill battle in New Jersey, Virginia ought to be favorable territory — after all, the GOP won every statewide office there just four years ago with Glenn Youngkin atop the ticket.

But it’s Youngkin and company, not Trump, who are on the verge of forfeiting Virginia to the Democrats this year.

What went wrong is a tale of botched succession and inadequate intra-party competition.

Republicans nationwide need to pay heed to the Virginia party’s self-immolation.

The big story isn’t the sex scandal engulfing the GOP’s openly gay candidate for lieutenant governor, John Reid.

It’s not even the role Youngkin and the head of his Spirit of Virginia PAC — who’s since had to resign — played in promoting the scandal in a botched effort to force Reid to drop out.

Sex and betrayal make great headlines, but the lieutenant governor’s race — and Reid’s apparent dalliances with drag queens and pornography — is a sideshow: The race that matters most is for governor.

With term limits preventing Youngkin from succeeding himself, his lieutenant governor, Winsome Earle-Sears, expected to get her turn at the top of the ticket.

And she has: The primary isn’t until next month, but because Earle-Sears’ challengers dropped out before the deadline to appear on the ballot, she’s the default nominee.

In fact, there’s no primary competition for any statewide office, although a challenger to Reid who gave up earlier, businessman John Curran, is now attempting a write-in campaign.

Republicans in Virginia, like those in many other places, think competition is a fine thing except when it comes to their own races.

And the major factions of the party, which until recently were the Christian right and country-club moderates, have long preferred to settle their differences in the close confines of party conventions rather than in primaries.

The rise of MAGA hasn’t changed much: Reid seemed unbeatable before the Youngkin circle exposed his antics because he’s a talk-radio host popular with the populist right.

But the party’s habit of quashing competition applied even to him, until Youngkin’s coterie changed their mind (and changed it too late — Reid is still probably unbeatable in the primary, only now much weaker in the general election).

Each well-managed faction preferred not to have a primary fight, so all of them together avoided one, deferring to Earle-Sears as the next in line for the marquee spot on the ticket.

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That was a mistake.

Earle-Sears was reassuring to the party’s right wing four years ago, as a black woman (and immigrant from Jamaica) in the post-George Floyd era who’d served in the United States Marine Corps and was outspokenly anti-abortion and supportive of gun rights.

Moderates might have perceived her as inexperienced — she’d served two years in the House of Delegates in the early 2000s — but Youngkin’s coattails with centrists carried Earle-Sears and the rest of the ticket to victory.

Once in office, however, Earle-Sears made some rookie mistakes, looking ahead to running for governor in her own right by trying to court the moderates who weren’t so keen on her — while losing support with right-wingers, especially once she started to opine on national politics.

“I could not support him. I just couldn’t,” she told Fox News in 2022 about the possibility of another Trump bid for the White House.

“A true leader understands when they have become a liability,” she said.

She felt differently by the time Trump locked up the GOP presidential nomination last year, but the damage with MAGA voters was already done.

The result was that Earle-Sears remained too well-positioned to challenge , but is ill-prepared to maximize conservative turnout or win moderates the way Youngkin did.

“John Reid is the Republican nominee for Lt. Governor. It is his race and his decision alone to move forward,” she stated on Facebook.

“We all have our own race to run.”

She trails the presumptive Democratic nominee, Abigail Spanberger, in all early polls by an average of nearly 7 percentage points.

Earle-Sears and Reid both needed the kind of close scrutiny they would have received in a competitive primary.

A tough primary might have weakened the eventual nominees — but they would hardly be weaker than they are now, and early exposure of their vulnerabilities might have allowed the party to pick better.

Primaries can be unruly, but if the GOP wants to avoid a rout next year, it will have to put its candidates to stricter tests than they’ve faced in Virginia.