KIMBERLY STRASSEL: Rise of the Mamdani Clones. “After the 2024 humiliation, the left is back. It could hurt the party in 2026.”

The left’s zeal is also propelling candidates into open and battleground races—no matter the general-election risks. Maine Rep. Jared Golden clung to his rural Maine district by less than 1 point as Mr. Trump won it by 10 last year, and only via a pragmatic voting record. The primary to replace him features two avowed progressives, racing to the left. And progressives are stacking up cash and endorsements in primaries to take on the most vulnerable Republicans in battleground states from Pennsylvania to Arizona and Wisconsin. In the contest to challenge vulnerable Republican California Rep. David Valadao, school-board activist Randy Villegas is using a Sanders endorsement and dollars to outpower moderate state Rep. Jasmeet Bains.

The risks of the Sanders takeover were further highlighted in Texas this week, when former Rep. Colin Allred was pressured out of a Senate run, to clear the decks for uber-progressive Rep. Jasmine Crockett. Mr. Allred, a former NFL linebacker, lost to Sen. Ted Cruz last year by 8 points, significantly outperforming Kamala Harris. Democrats have their best shot at a statewide office in Texas in years, given the general electoral climate and a bloody GOP primary between Sen. John Cornyn and state Attorney General Ken Paxton. Ms. Crockett still must beat state House member James Talarico, but backing for her is pouring in and Democrats face the real prospect that their “best” shot will be in the hands of a freshman Democrat who has clawed her way to notoriety through creative slanging matches.

Lost in all this maneuvering was the release of a recent report from a center-left group, Welcome, which Semafor reports “consulted hundreds of thousands of voters over six months for its broad findings, including that 70% of voters think the Democratic Party is ‘out of touch’ ” on issues ranging from transgenderism to climate—everything the reascendant progressive left stands for.

Well, they are. But that doesn’t mean the GOP can play dead and expect to win.