Twenty-four delegates are at stake. Right now, candidates Barack Obama and Hillary Rodham Clinton are separated by only 25 delegates, with Clinton having the slight lead.
Both candidates made personal appeals for votes in the state Saturday.
Massachusetts Governor Deval Patrick, Rhode Island Congressman Patrick Kennedy and Massachusetts Senator John Kerry are visiting caucuses on Obama's behalf.
Maine Governor John Baldacci, Massachusetts Congressman Jim McGovern and New York Congressman Gregory Meeks are campaigning for Clinton.