Michigan Democrat Mallory McMorrow suspended her campaign for the U.S. Senate on Sunday, transforming her party’s high-stakes nomination contest just a month before the primary.

McMorrow did not explain her unexpected decision in the announcement she posted on social media, but she was under intense pressure from some in her party to help create a two-person race between U.S. Rep. Haley Stevens and progressive favorite Abdul El-Sayed.

The seat being vacated by Democratic Sen. Gary Peters is one that the party must hold if it hopes to reclaim the Senate majority in this fall’s midterm elections.

“Today, I’m announcing that I am suspending my campaign for United States Senate,” McMorrow wrote.

“And I’m doing it with a deep, deep sense of gratitude. For our thousands of volunteers, for everyone who donated what you could — building a campaign with zero corporate PAC dollars. For my staff, who built this team up from nothing. I thank you,” she said.

The Aug. 4 race has increasingly split Democrats along ideological lines, with Senate Democratic leader Chuck Schumer backing Stevens and El Sayed drawing the support of Vermont Sen. Bernie Sanders and allies such as Rep. Alexandria Ocasio Cortez, D-N.Y., although El-Sayed identifies as a progressive rather than a democratic socialist.

Some establishment Democrats feared that his far-left policies might undermine the party’s chances in the high-profile general election this fall.

With McMorrow out of the race, the establishment believes El Sayed will be easier to defeat.

The primary winner is expected to face Republican Mike Rogers, who lost to now-Sen. Elissa Slotkin in 2024.

Steve Peoples, The Associated Press