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As Hillary Clinton works to win over Bernie Sanders supporters, her campaign has hired a senior Sanders aide to lead outreach efforts with progressive groups and activists.

Nick Carter will serve as Vermont state director and national progressive outreach coordinator for Hillary for America, the campaign confirmed to NBC News.

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Carter was one of Sanders’ early political hires, running the senator’s political action committee months before the launch of his presidential campaign.

Carter, who served as Sanders’ political outreach director, addressed a conference call of Clinton convention delegates last week on “the importance of party unity,” according to an email invitation to the call, which featured Rep. Raul Grijalva.

Carter is the most senior Sanders staffer to join the Clinton campaign yet announced. The campaign previously hired Kunoor Ojha to help mobilize young voters.