DETROIT — The contest for the Michigan House seat once held by the late, long-serving Congressional Black Caucus cofounder John Conyers pits two unlikely characters against each other — and the black Republican in the race tells The Post it highlights a danger for Donald Trump.

In the blue corner is Democratic Rep. Shri Thanedar, the 69-year-old Indian-American representing America’s blackest big city in Congress.

In the red corner is the underdog, Martell Bivings, a 37-year-old black Republican seeking an upset victory this November.

The very existence of a candidate like Bivings is most unusual in deep-blue Detroit, where a Republican hasn’t held an elected position since Keith Butler served on Detroit City Council in the 1990s. Bivings has raised less than $24,000 so far and has about $11,000 in the bank, according to Open Secrets.

Thanedar rose to prominence in 2018 during the Democratic primary race for governor, when he ran against Gretchen Whitmer, who went on to win the primary and the office.

But Thanedar pulled more votes in Detroit than Whitmer did. Since then he’s won his last two races, first for the Michigan House, then for Congress.

Outside his boyband hairstyle, which has drawn speculation he wears a toupée, Thanedar is best known for burying his opponents in cash. The businessman and scientist wrote his campaign a $5 million check to win the 2022 House race.

As of last report, Thanedar raised $7 million for this year’s contest and still has $4.8 million in the bank.

In addition to the Goliath Thanedar, who easily dispatched a Detroit councilwoman, Mary Waters, in his primary, Bivings faces another obstacle: a lack of belief among Republicans that his race is worth investing in.

The 2024 contest is a rematch of the 2022 race, which Thanedar won 71% to 24%, by a margin of 110,000 votes.

As Bivings noted at a recent fundraiser in suburban Detroit: “I don’t become a threat until election night at 8 p.m.”

Republicans view it the same way.

A source familiar with the thinking of national Republicans told The Post the National Republican Congressional Committee will target about 37 races this year.

The four in Michigan are Paul Hudson vs. incumbent Hillary Scholten in west Michigan; incumbent John James’ rematch against Carl Marlinga in Macomb County; Tom Barrett’s race against Curtis Hertel in the Lansing area, for the seat vacated by Senate hopeful Elissa Slotkin; and Paul Junge’s matchup against state Sen. Kristen McDonald Rivet. That last, Flint-area seat has been held by a single family, the Kildees, since the late 1970s — first by Dale, then by his nephew Dan, who’s not running for re-election.

David vs. Goliath — rather, Bivings vs. Thanedar — does not fit the NRCC criteria, the source said. Republicans want to invest in races with a 4-point margin or smaller. Not invest in the impossible dream.

Another source, a Republican consultant, told The Post Bivings needed to make the “business case” for more help from the party.

“If he could say ‘I’d bring Donald Trump 3 points in Detroit,’ that might be worth it,” the source said.

The candidate told The Post the national thinking doesn’t take into account the local sentiment.

“My qualitative hunch tells me that the more impoverished a neighborhood, the more likely it is to vote Republican,” Bivings said. “Nobody is basking in poverty.”

That hunch has found few buyers among the donor class. Bivings said he’s had five-figure donors with a history write $200 checks instead.

Bivings has heard the optimistic talk among Republicans that Donald Trump might pull 20% of the black male vote in cities like Detroit. Don’t count on it, he warns.

“I know those black men. I’m related to those black men,” Bivings said. “They’re not going to go to the polls. They’ll say ‘I ain’t make to the polls; was Election Day last week?'”