The 2012 United States House of Representatives elections in Maine were held on Tuesday, November 6, 2012, to elect the two U.S. representatives from the state of Maine, one from each of the state's two congressional districts. The elections coincided with the elections of other federal and state offices, including a quadrennial presidential election and an election to the U.S. Senate. Democrats would not win both of Maine's congressional districts again until 2018.
Unlike most states, which had passed redistricting laws to redraw the boundaries of their congressional districts based on the 2010 United States census in advance of the 2012 elections, Maine law required that redistricting be done in 2013. In March 2011, a lawsuit was filed asking a U.S. district judge to ensure redistricting is completed in time for the 2012 elections. According to the Census, the 1st district had a population of 8,669 greater than that of the 2nd district. The Maine Democratic Party, which opposes the lawsuit, was granted intervenor status, and argued that the lawsuit constituted an attempt by the Maine Republican Party to force Representatives Chellie Pingree and Mike Michaud, both of whom are Democrats, to run in the same district. On June 9, 2011, a panel of three federal judges agreed that failing to redistrict would be unconstitutional, and that the state should redraw the boundaries of its districts immediately.
Governor Paul LePage called a special session of the Maine Legislature on September 27 to consider a redistricting plan. On August 15, both Republicans and Democrats released redistricting proposals. The Republican plan would move Lincoln County, Knox County (including Pingree's hometown of North Haven) and Sagadahoc County from the 1st district to the 2nd, and move Oxford County and Androscoggin County from the 2nd district to the 1st, thereby making the 2nd district more favorable to Republicans. The Democratic plan, meanwhile, would not significantly change the current districts: only Vassalboro would be moved from the 1st district to the 2nd.
Democrat Chellie Pingree, who had represented Maine's 1st congressional district since 2009, was gathering signatures to run for the U.S. Senate, but she decided not to run. State senator Cynthia Dill and state representative Jon Hinck, both of whom are Democrats, picked up petitions to run in the 1st district. However, after Pingree stepped out of the Senate race, Dill and Hinck returned, campaigning for U.S. Senate.
Democrat Mike Michaud, who had represented Maine's 2nd congressional district since 2003, decided not to run for the U.S. Senate, and was running for a sixth term in the United States House of Representatives. David Costa, a concierge at the Portland Harbor Hotel; Wellington Lyons, a lawyer; and David Lemoine, a former state treasurer, had taken out papers to seek the Democratic nomination to succeed Michaud had he run for Senate. Emily Cain, the minority leader of the Maine House of Representatives, had also planned to seek the Democratic nomination in the 2nd district if Michaud decided to run for the Senate seat.