PORTLAND, Maine (AP) — Graham Platner on Friday submitted his paperwork to formally withdraw from Maine’s U.S. Senate race, officially ending an upstart yet troubled campaign whose dissolution threatens Democrats’ pursuit of chamber control.

Platner’s paperwork was received by the Maine secretary of state’s office and reflected shortly thereafter in its online withdrawal list.

In a letter to the secretary of state’s office, which Platner also posted on social media, he wrote that the Mainers who had nominated him “voted for a new kind of politics” that is “representative of people down here in the real world — not billionaires, oligarchs, or the political establishment.” It was the same outsider chord that had been a trademark of his tumultuous campaign, in which Platner drew backing from progressive leaders including Vermont Sen. Bernie Sanders and U.S. Rep. Ro Khanna of California.

“I seek to further the movement we have built together and the future we believe in,” he went on, without detailing what that meant.

Maine is considered a key state for control of the narrowly divided Senate, and Democrats were desperate for a candidate capable of defeating Republican Sen. Susan Collins.

The formal withdrawal comes two days after Platner said he would quit the race, facing an allegation of sexual assault that he has denied. Maine Democrats are seeking a new nominee, and several hopefuls have already begun jockeying for position.

State law includes a provision for Democrats to replace Platner before the general election but the replacement must by named by July 27.

Just before Platner’s Wednesday announcement, more than 100 state Democratic Party committee members signed off on holding a nominating convention, in the event of his withdrawal, to choose the nominee. The state party has not publicly released details of when the convention will be held.

Several Democrats have announced runs for the Senate nomination this week. They include three candidates who lost the June primary for the governor nomination — former Maine Center for Disease Control and Prevention director Nirav Shah, Secretary of State Shenna Bellows and former Maine Senate President Troy Jackson.

Others who have announced runs include Maine Beer Company co-founder Dan Kleban; former 2nd Congressional District candidates Jordan Wood and Paige Loud; state Rep. Valli Geiger; and former Maine Senate candidates David Costello and Andrea LaFlamme.

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Kinnard reported from Columbia, South Carolina.

Meg Kinnard And Patrick Whittle, The Associated Press