Inside the Abdul El-Sayed-Haley Stevens Meltdown in Michigan

The last straw for Representative Haley Stevens came Saturday afternoon.

She was on the cusp of appearing at a unity event with Dr. Abdul El-Sayed, who defeated her in a summer primary and became Michigan’s Democratic Senate nominee. Several powerful intermediaries had been trying to broker peace between the former rivals, who were sparring over Dr. El-Sayed’s strong criticisms of Israel.

But after Ms. Stevens issued a hostile statement Friday morning calling upon Dr. El-Sayed to condemn an ad made by a supportive PAC and make other concessions, he stepped before reporters and said what his campaign had been signaling privately: He no longer wanted Ms. Stevens to join him at a Detroit church on Sunday.

It was one thing not to be welcomed by Dr. El-Sayed’s Senate campaign. It was quite another for him to say so in public.

So Ms. Stevens on Sunday did what she had been telling everyone she would not do. She endorsed former Representative Mike Rogers, Dr. El-Sayed’s Republican opponent in a race critical to control of the Senate.

“Abdul made very clear that I was not welcome in his campaign, that he didn’t need me there, that he didn’t want me there,” Ms. Stevens said while standing next to Mr. Rogers outside a Black church in Detroit, where they had just attended the Sunday service. “I did endorse the Democratic nominee, and he chose to close this campaign by saying I wasn’t welcome. I’ve never been invited to a campaign event. That’s fine. You know, he’s busy. He’s running all around.”