WASHINGTON — Crucial US swing voters have become increasingly troubled by the rise of the Democratic Socialists of America and the far-left in general — a major warning sign for Dems ahead of the midterms, a new poll shows.

When asked about their views of the DSA, 56% of respondents indicated they had an unfavorable view, up from 50% in September, according to Americans for Prosperity’s latest “Americans Unscripted” report.

Nearly 60% also felt the Democratic Party was controlled by the far left, again up from 50% in September, and 82% indicated they favor personal freedom and free markets over government control.

“Swing voters are souring on socialism — and fast,” AFP spokeswoman Katelyn Bledsoe told The Post.

“That’s a real opening for Republicans, and the candidates who show voters a credible plan to bring their costs down are in the strongest position on November 3.”

Americans for Prosperity, a libertarian-leaning policy advocacy group associated with the billionaire Koch brothers, has been leaning on its network of organizers across the country to get a pulse check. This is its last “Americans Unscripted” report before the Nov. 3 elections.

The question about the DSA was asked to about 9,000 to 10,200 people in eight states: Alaska, Iowa, Michigan, Montana, New Hampshire, North Carolina, Ohio and Wisconsin.

Critically, the trend from September to October indicates that swing voters who will be deciding key races are increasingly turning on the far left.

“Nothing is free,” a man named Michael from Holland, Mich., told an Americans for Prosperity volunteer, according to the report. “There’s an agenda behind all these promises of free benefits.”

Still, there are some red flags for Republicans in the survey as well.

Strikingly, 45% of respondents sampled indicated they trusted Democrats more on cost of living issues, compared to 36% who said Republicans and 18% who said neither.

That marks a turnaround from August, when Republicans had a 44% to 39% edge over Democrats.

A myriad of polls have consistently shown that cost of living concerns are top of mind for voters heading into the midterms, including gas prices and inflation.

“Inflation and fuel costs are squeezing my business,” said Nick, a contractor in New Hampshire, to AFP.

AFP’s latest “America Unscripted” report included conversations with 81,673 voters from Oct. 1–16 in those eight states.

Republicans are widely seen as the underdogs in the battle for control of the House of Representatives and increasingly the Senate as well, according to top forecasters.