The GOP is outright boasting about how redistricting gave the party its majority in the U.S. House of Representatives.
A recent memo by the Republican State Leadership Committee called "How a Strategy of Targeting State Legislative Races in 2010 Led to a Republican U.S. House Majority in 2013," said the GOP spent more than $30 million in 2009-2010 to help win key statehouse victories. This gave Republicans control of redrawing legislative districts in states like Michigan, Ohio, Pennsylvania, and Wisconsin that led to the House GOP holding on to its majority in the 2012 elections.
"The rationale was straightforward," the memo said. "Controlling the redistricting process in these states would have the greatest impact on determining how both state legislative and congressional district boundaries would be drawn. Drawing new district lines in states with the most redistricting activity presented the opportunity to solidify conservative policymaking at the state level and maintain a Republican stronghold in the U.S. House of Representatives for the next decade."
So while Democrats won the Senate and the White House, House Republicans wound up with a 33-seat majority because of its plan known as the Redistricting Majority Project or "REDMAP." The RSLC memo says the victory occurred even though "Democratic candidates for the U.S. House won 1.1 million more votes than their Republican opponents."
Via Talking Points Memo and the Republican State Leadership Committee