Stevens endorsed Rogers after attending a Detroit church service with him.
The remarkable show of support for the US President Donald Trump-backed candidate in the tightly contested race comes after she was uninvited to a joint event the same day with El-Sayed, who defeated the congresswoman by a slim margin in the August primary.
“Our Democratic nominee for Senate said I was no longer welcome in his campaign and that I should stay away,” Stevens said in a video announcing the endorsement, which led her top aide to quit.
“And he’s right. And that’s why I am endorsing Mike Rogers for the United States Senate today.”
El-Sayed dismissed the endorsement when asked about it by reporters later Sunday, saying he’s focused on issues voters care about, such as the high cost of living.
“At the end of the day I actually don’t think about Haley Stevens,” he said, adding later: “None of this matters.”
Michigan Democratic leaders were left shocked.
With less than 48 hours to go before Election Day, a party that had spent months trying to unite behind its Senate nominee was suddenly grappling with an extraordinary defection in one of this year’s most important races.
Tensions between the two Democrats have festered since the primary.
Stevens is a staunch supporter of Israel, while El-Sayed is a fierce critic of the US ally.
He has also been criticised by some in the community for past remarks regarding a Michigan synagogue attack and for appearances with controversial streamer Hasan Piker.
El-Sayed, a former Michigan public health official, is facing Rogers, an ex-congressman, for the seat held by the retiring Democrat, Gary Peters.
Keeping Michigan in Democratic hands is vital to the party’s effort to win a majority for the final two years of Trump’s second term. (AP)
