MANCHESTER, N.H. — Embittered “Never Trump” Republicans tied to former Ohio Gov. John Kasich have secretly schemed to assist Joe Biden’s campaign — because they think he’s the only Democrat who can beat the president and help them get “revenge,” The Post has learned.

Emails obtained by The Post show that two top staffers from Kasich’s failed, 2016 primary campaign and Ohio’s former GOP chairman, a Kasich ally, were among those involved in efforts to boost support for the former vice president in last week’s botched Iowa caucus and Tuesday’s New Hampshire primary.

Funding for the plan came largely from two deep-pocketed Democratic donors — former Microsoft president Jon Shirley and his wife, Kimberly — who’ve made maximum contributions to Biden and hosted a fund-raiser for him last year, records also show.

“They think Biden is the only candidate who can beat Trump at the general election,” said a GOP source familiar with the strategy.

Documents attached to one email show the group planned to identify and target at least 5,000 Democrats “from the conservative voter base” in each of Iowa’s four congressional districts, then use that information in “suppression, persuasion and GOTV [get out the vote] efforts.”

That project failed miserably, with Biden coming in a distant fourth place last week.

In New Hampshire, documents show, the group planned to use automated “IVR technology,” or interactive voice response polling, to identify Republicans and “previously identified” Republicans willing to cross party lines and vote for Biden in the primary.

But the proposal by Michael Stroud, a Republican political operative from Michigan, wasn’t circulated until mid-November, weeks after the Oct. 25 deadline for New Hampshire voters to change their registration ahead of the primary.

In the Granite State, only Democrats and “undeclared” voters can vote in the party’s primary.

A senior GOP source called the group’s half-baked ideas “dumbfounding.”

“They’re not rational people,” the source said. “They want revenge. Trump beat them and they want revenge.”

Key figures in the effort include Jeff Polesovsky and Ben Kaiser — who were the national political director and deputy legislative director, respectively, for Kasich’s 2016 campaign — and former Ohio GOP chairman Matt Borges, who backed Kasich in the primary.

Following Trump’s victory in the general election, the president-elect personally intervened to oust Borges in January 2017.

At the time, Borges had the support of Kasich, who refused to endorse Trump following his primary loss.

Emails show the group’s pro-Biden operations would be paid for by a political action committee, Defenders PAC, which was established in September.

Defenders PAC received $75,000 — virtually all of its funding — from Jon and Kimberly Shirley, according to its most recent Federal Election Commission filing.

The PAC’s only other contributor was Borges, who kicked in $1,000, according to FEC records.

Borges told The Post that he wasn’t trying to defeat Trump, but instead wanted to ensure that Vermont Sen. Bernie Sanders didn’t become the Democratic nominee.

“To some extent, it’s unclear how vulnerable President Trump might be and the last thing any of us want is to have a socialist president,” he said.

Borges also claimed that his group was only targeting anti-Trump Republicans who were likely to sit out the November election.

No one else associated with the effort returned requests for comment.

Biden has all but written off his chances in New Hampshire, admitting during Friday’s that “I took a hit in Iowa and I’ll probably take one here.”

The latest Real Clear Politics polling average has Biden tied for fourth, with Sanders the likely victor.