Mitt blew it, and blew all of 2012, he depressed turnout.
Once he got the nomination Romney came out against the GOP pro-life platform, reaffirmed his support for homosexual scout leaders, and ran pro-choice ads in Ohio, Virginia, and Wisconsin, losing all three of those states.
The whole campaign was one lie after another. A lefty pretending to be severely conservative, when everyone knew he was lying, was never going to win.