Michigan Democrat Haley Stevens, who narrowly lost the Senate primary to Abdul El-Sayed in August, endorsed Republican Mike Rogers just two days before Tuesday's midterm election, making a surprise appearance alongside him in Detroit.

According to the BBC, Stevens had told CNN as recently as Saturday night that she was sticking with El-Sayed, then defended the reversal Sunday saying simply: "I changed my mind." She said the decision followed a weekend fallout in which El-Sayed's campaign disinvited her from a joint event.

Per the BBC, some of her staff reportedly resigned immediately after the announcement.

The backlash was swift and senior. Senate minority leader Chuck Schumer called the move "a despicable betrayal," posting that Democrats were united behind El-Sayed while Rogers was "a tool of Donald Trump and billionaire donors."

Nancy Pelosi wrote that Stevens had "dangerously betray[ed] Michigan families' healthcare, freedoms and future."

According to the Guardian, New York mayor Zohran Mamdani said working-class people's lives were on the ballot and Stevens had betrayed them, while Michigan Democratic Party chair Curtis Hertel declared Stevens "not a current member of the Michigan Democratic Party, nor will she be in the future."

Debbie Dingell dismissed the move as Stevens' "continued efforts to get attention."

The feud traces to an outside liberal group's campaign ad linking US living costs to American support for Israel. Stevens demanded El-Sayed condemn it; the Guardian reports his campaign disinvited her after she said she would appear at an event only if he denounced it.

BBC notes El-Sayed said he had nothing to do with the ad and disagreed with its contents.

On the other side, Trump praised Stevens on Truth Social as a "highly respected Democrat" and, per the Guardian, welcomed her to join the Republican Party at a Dubuque rally, calling her loyalty "almost unprecedented." Rogers himself said the endorsement showed "courage."

Michigan is considered critical to Democrats' hopes of capturing the US Senate, and the seat is currently in Democratic hands; according to the BBC, analysts say the party must retain it and flip a handful of others to gain control and challenge Trump in his final two years.

El-Sayed, who would be the first Muslim person elected to the US Senate, has been attacked by Trump, who the BBC reports called him a "jihadist" without evidence, prompting accusations of Islamophobia.

Asked about the endorsement, El-Sayed told reporters Sunday: "I don't think about Haley Stevens. None of this matters." Jewish Democratic nominees Brad Lander and Daniel Bliss, per the Guardian, urged voters to back El-Sayed.