Graham Platner's campaign manager on Wednesday accused the Maine Democratic Party of coordinating with national Democrats "behind closed doors" and cutting the embattled US Senate nominee's supporters out of the process to determine his potential replacement in the wake of a sexual assault allegation—and amid expectations that he will soon drop out of the race.In a text message sent to Platner supporters, campaign chief Ben Chin wrote that the Maine Democratic Party "allowed the DC-based Democratic Senatorial Campaign Committee to send staffers to plan a potential nominating process behind closed doors. Both the state and national parties cut our team, our volunteers, and our vast networks of supporters out of the conversation completely.""We firmly believe that the supporters and volunteers who built this movement deserve to have a real role in any nomination process," Chin's message continued. "If the Maine Democratic Party hopes to harness our movement, and avoid disillusioning the hundreds of thousands of supporters who came into the fray because of our movement’s policies, it must consult the feedback and proposals of the people who built and sustained this."The text included a link to a two-question survey asking Platner volunteers, "What message do you have for the Democratic Party?" and, "What message do you have for Graham?" The defiant message came as Platner's campaign was reportedly planning the nominee's exit from the US Senate race to pave the way for a different Democratic candidate to take on five-term Sen. Susan Collins (R-Maine) in November. Platner has denied the sexual assault allegation that prompted mass calls for him to exit the race, including from his most prominent supporters such as Sen. Bernie Sanders (I-Vt.). Chin's text message was circulated a day after Devon Murphy-Anderson, the Maine Democratic Party's executive director, said in a video posted to social media that the party has been "working around the clock" to develop a plan to replace Platner that is "open, inclusive, transparent, and fair." The party has not yet publicly specified what that plan could entail, saying Platner must formally withdraw from the race first.Murphy-Anderson accused Platner's team of "repeatedly reach[ing] out" to the Maine Democratic Party "in an attempt to put their thumb on the scale of what this process looks like.""We have repeatedly reiterated to Graham Platner's team that they have no role in determining our next Democratic nominee for the US Senate," Murphy-Anderson added.In response to Murphy-Anderson's statement, the Platner campaign denied that it has attempted to exert influence over the replacement process, saying it simply "reached out to the party to try and understand what this process would look like.""Over 150,000 Mainers voted for this movement, and over 15,000 Mainers volunteered their time and energy to it," an unnamed Platner campaign official told NBC News late Tuesday. "While Graham wouldn't want to be a part of the process, he would want to make sure the voters and volunteers make this decision—not the political establishment."On Wednesday, the Maine Democratic Party issued a new statement decrying what it called the Platner team's "false accusations against us" while also expressing gratitude for "his supporters and all of their efforts to defeat Susan Collins.""They are a vital part of our party and deserve to participate in an open process to select Platner’s replacement," said Maine Democrats.CNN reported that Platner is "expected to announce his decision" on his candidacy "through a recorded video, which could come later Wednesday."Platner must drop out of the race by July 13 if he's to be replaced on the November ballot. If he exits the race, an alternative must be selected by July 27.Politico reported that Platner "quietly fielded a poll Tuesday gauging the strength of people who could replace him on the ballot.""The flash poll, obtained by Politico, was conducted by Public Policy Polling and commissioned by Platner’s campaign," the outlet reported. "It tested head-to-head match-ups between Republican Sen. Susan Collins and Platner, along with five possible Democratic replacements for Platner, including former Maine state Senate President Troy Jackson and Secretary of State Shenna Bellows.""Of the Democrats tested, Jackson performed the best, leading Collins 49% to 44%, with 7% of voters undecided," Politico reported. The outlet also noted that the poll, conducted the day after the sexual assault allegation against Platner was first reported by Politico, showed Platner trailing Collins 47% to 42%.Jackson has filed paperwork to explore a Senate bid in preparation for Platner's expected exit, and Bellows—who lost badly to Collins in 2014—has said she would "seriously consider entering this race." Nirav Shah, former director of the Maine Center for Disease Control and Prevention, is also weighing a Senate bid.