July 5 (UPI) — Mallory McMorrow, a state lawmaker who made in early splash in the race for the Democratic nod in Michigan’s key U.S. senate race, suspended her campaign on Sunday in a surprise move.

McMorrow, who positioned herself between the national party leadership favorite Rep. Haley Stevens and progressive challenger Abdul El-Sayed, said in a social media post she is pulling out of the race “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,” she said, adding that while she is suspending her campaign, “I am not leaving the fight.”

McMorrow reiterated her call for “new leadership and a better Democratic Party,” whose top voices, including Senate Minority Leader Chuck Schumer, have endorsed Stevens to take on the Republican nominee, former Rep. Mike Rogers, in November’s general election.

Her withdrawal leaves Stevens and El-Sayed as the remaining candidates for the Aug. 4 primary, which is now shaping up to be a major test of whether El-Sayed can extend progressives’ winning streak against more establishment figures in Democratic primaries.

“Whoever wins this primary on August 4th will have my full support,” she declared.

The Michigan race is seen as a key in the Democrats’ hopes of capitalizing on the unpopularity of President Donald Trump and flipping the Senate from Republican control in November. To do so, they must keep it in the “blue” column as it is being vacated by Democrat Gary Peters.

McMorrow was an early front-runner in the race and had raised more than $8.6 million by the end of March but has since fallen behind El-Sayed and Stevens in the polls, the Detroit Free Press reported.

El-Sayed, a former Detroit public health official who has the backing of progressive stalwarts Sen. Bernie Sanders and Rep. Alexandria Ocasio-Cortez, has seen a surge of support since May and last month won the endorsement of the United Auto Workers.

Four-term congresswoman Stevens, meanwhile, is picking up backing from some of McMorrow’s supporters, including Michigan Attorney General Dana Nessel, who on Sunday called Stevens “a seasoned fighter for Michigan who knows how to work in a difficult environment to get essential policies across the finish line.”