Although Democratic candidates received a nationwide plurality of more than 1.4 million votes (1.1%) in the aggregated vote totals from all House elections,[3] the Republican Party won a 33-seat advantage in seats, thus retaining its House majority by 17 seats. Democrats picked up 27 previously Republican-held seats, but most of these gains were canceled out due to Republican pick-ups of Democratic-held seats, and reapportionment gains that benefited Republicans, leaving the Democrats with a net gain of just eight seats.[4]
This disparity – common in close elections involving single-member district voting[5] – has sometimes been attributed to targeted Republican gerrymandering in the congressional redistricting process following the 2010 United States Census.[6][7][8][9][10] "Unintentional gerrymandering," --the high concentration of Democrats in urban centers--leading to "wasted votes" in districts that easily elected Democratic candidates, has also been cited as causing some of the efficiency gap.[11][9][12] The GOP also benefited from having a greater number of incumbents, who tend to have an advantage in elections[9] which may have helped Republicans win close elections for individual seats.
In the 20th century, the party with a plurality of the popular vote was unable to receive a majority in the House on four occasions- 1952 and 1996, in which the Republicans held a majority in the House. Meanwhile, the 1914 and 1942 elections were the last time that the Democrats won a majority in the House without winning the popular vote.[8][13]
As of 2024, this is the last congressional election in which Democrats won a House seat in West Virginia.
Forty-one Representatives retired. Thirty-four of those seats were held by the same party, six seats changed party.
Democrats
Twenty-two Democrats retired. Fourteen of those seats were held by Democrats, five were won by Republicans, and three seats were eliminated in redistricting.
Nineteen Republicans retired. Fifteen of those seats were held by Republicans, one was won by a Democrat, and three seats were eliminated in redistricting.
As a result of redistricting, many incumbents were forced to compete against each other in the same district, which resulted in a larger number of incumbents being defeated in primaries.
In primary elections
Thirteen representatives lost renomination: Eight were lost in redistricting battles pitting incumbents against each other, and five incumbents lost nomination to non-incumbent challengers.
Democrats
Seven Democrats lost renomination: five in redistricting and two to a non-incumbent challenger.
Seat held by a Democrat
These primary winners later won the general election.
Ten incumbent Democrats lost re-election; four to fellow Democrats and six to Republicans. Four losses were in California: two due to redistricting putting two incumbents together (resulting in a net loss of two for the Democrats) and two due to the state's top two primary. Two incumbents outside of California lost to Republican incumbents after being redistricted to the same district.
The 2010 United States census determined how many of the 435 congressional districts each state receives for the 2010 redistricting cycle. Due to population shifts, Illinois, Iowa, Louisiana, Massachusetts, Michigan, Missouri, New Jersey, and Pennsylvania each lost one seat; and New York and Ohio each lost two seats. Conversely, Arizona, Georgia, Nevada, South Carolina, Utah, and Washington each gained one seat; Florida gained two seats; and Texas gained four seats.[51]
New seats
Twelve new districts were created after the 2010 redistricting process:
There were six special elections in 2012. Winners would have a seniority advantage over other freshmen. Two elections were held separate from the November elections and four elections were held concurrent with the November elections.
Incumbent resigned July 31, 2012 for family health reason. New member elected November 6, 2012. Republican hold. Winner was also elected the same day to the next term, see below.
Incumbent resigned July 6, 2012 after failing to qualify for renomination. New member electedNovember 6, 2012. Democratic gain. Winner was not elected the same day to the next term, see below.
Incumbent died March 6, 2012. New member electedNovember 6, 2012 to finish his father's term. Democratic hold. Winner was also elected the same day to the next term, see below.
Incumbent resigned March 20, 2012 to run for Governor of Washington. New member elected November 6, 2012. Democratic hold. Winner was also elected the same day to the next term, see below.
Arizona gained one seat in reapportionment. A second open seat was created when a pair of Republicans were redistricted into the same district.[55] Primary elections were August 28, 2012.
California retained its fifty-three seats: four new seats were created when four pairs of Representatives were redistricted to run against each other. An additional Republican incumbent, Gary Miller, won re-election in an entirely different district from the one he had previously represented.[56] The election featured the first use of the top-two primary system in which primary elections list candidates from all parties on one ballot, and the top two vote-getters advance to the general election. Two elections (30th and 44th districts) featured two Democratic incumbents running against each other.[57]
Florida gained two seats in reapportionment. As a result of the Fair Districts Amendment, approved by voters via referendum in 2010, the legislature could not take incumbency into account in drawing the lines.[58] As a result, two incumbent Republicans, John Mica and Sandy Adams, were drawn into the same district, creating a third new seat.[59]
Massachusetts lost one seat in reapportionment, forcing a pair of incumbent Democrats into the same district, although one, John Olver, retired in advance of the legislature's approval of new maps. Primary elections were held September 6, 2012.
Thad McCotter (R) resigned July 6, 2012, after failing to qualify for renomination. New member elected. Republican hold. Winner was not elected the same day to finish the current term, see above.
Donald M. Payne (D) died March 6, 2012. New member elected. Democratic hold. Winner was also elected the same day to finish the current term, see above.
New York lost two seats in reapportionment. After the legislature failed to reach agreement, New York conducted its 2012 congressional elections under a map drawn by a federal magistrate judge. Two incumbent Representatives saw their districts eliminated; one, Maurice Hinchey, chose to retire, while the other, Bob Turner, chose to run for the U.S. Senate.[62] A third incumbent impacted by redistricting, Gary Ackerman, chose to retire, creating an open seat.[63]
Pennsylvania lost one seat in reapportionment, forcing two incumbent Democrats to run against each other, with the seat ultimately being won by a Republican challenger in November.
Texas gained four seats in reapportionment. After the initial redistricting map drawn by the Texas Legislature was denied pre-clearance by a federal district court under Section 5 of the Voting Rights Act, Texas conducted its 2012 congressional elections under a court-ordered interim map.[65]
Jay Inslee (D) resigned March 20, 2012 to run for Governor of Washington. New member elected. Democratic hold. Winner was also elected the same day to finish the current term, see above.
Puerto Rico's Resident Commissioner is elected to a four-year term during U.S. presidential election years. It is the only seat in the House elected for a four-year term.
^"...the discrepancy between the popular vote won by a party and the seats that party wins in Congress is an endemic feature of our political system." Trende, Sean. Why Republicans Lost the Vote But Kept the House. RealClearPolitics. 2013-05-16. Retrieved 2013-09-15.
Foreman, Sean D., and Robert Dewhirst, eds. Roads to Congress, 2012 (Lexington Books; 2013) 326 pages; covers the 2012 Congressional races, as well as campaign finance, redistricting, and "voter suppression" laws.