WASHINGTON — Michigan Democratic Rep. Haley Stevens appeared with Republican Senate candidate Mike Rogers at a Detroit church Sunday in a stunning defection after a massive, public falling-out with Democratic nominee Abdul El-Sayed.

Stevens’ gesture comes at a critical time in the Michigan Senate race, which polls say is one of the tightest in the country.

Stevens lost the Michigan Senate Democratic nomination to left-wing El-Sayed by one percentage point.

She was initially supposed to attend a unity rally with El-Sayed on Sunday — before making the surprise appearance with his Republican rival.

Michigan Republican Senate candidate Mike Rogers, right, and Rep. Haley Stevens, D-Mich., attend a service at Perfecting Church Sunday in Detroit. AP Photo/Jose Juarez

Stevens’ appearance comes after clashes with former Dem rival and Senate candidate Abdul El-Sayed. AP Photo/Julia Demaree Nikhinson

But the two clashed late last week, prompting El-Sayed to gloat over his defeat of her in the primary and disinvite her to the Dem rally.

During her appearance with Rogers, Stevens touted her support for investing in black businesses.

“And that’s the policy that Mike’s going to take on,” she told reporters before entering the nave.

The shocking move marked the latest high-profile defection for El-Sayed, who has faced fractures in the Democratic coalition among Jewish and black voters in particular.