Maine Democrats have begun laying out the process for replacing Graham Platner as the party’s Senate nominee, as candidates race to assemble campaigns for a weekslong sprint to set up a marquee Senate matchup.

Platner posted a letter declaring his withdrawal of candidacy to social media on Friday afternoon, making official his announcement earlier this week that he would suspend his Senate campaign after an allegation of sexual assault, which he denies.

“In submitting this letter today, I seek to further the movement we have built together and the future we believe in,” Platner wrote.

The Maine Secretary of State’s Office confirmed receipt of Platner’s notice.

Officials have said Maine Democrats will hold a nominating convention, though it’s not yet clear when. The hopefuls so far include several people who ran unsuccessfully for other offices this year, giving most of them name ID with voters and a preexisting campaign infrastructure.