The 1988 United States Senate election in Maine was held on November 8, 1988. Incumbent Democratic U.S. Senator George J. Mitchell won re-election to a second full term. As of 2019, this is the last Senate election in Maine won by a Democrat. Angus King, who was elected in 2012 and reelected in 2018, is an independent who caucuses with the Democrats, but is not actually a member of the party.