Michigan Democrat Abdul El-Sayed’s former opponent in the U.S. Senate primary, Haley Stevens, stunned party officials Sunday by endorsing Republican Mike Rogers after Democratic tensions boiled over days before the election that could determine the balance of power on Capitol Hill.

Stevens endorsed Rogers after attending a Detroit church service with him. The remarkable show of support for Donald Trump’s 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 video announcing the endorsement. “And he’s right. And that’s why I am endorsing Mike Rogers for the United States Senate today.”