Two words: voter fraud.
No, we are not losing because of voter fraud. We're losing because we think we're losing because of voter fraud.
In November 2009, 52% of Republicans thought the 2008 election was stolen.
In December last year, 49% of Republicans thought the 2012 election was stolen.
This means fully half of the party thinks that they did everything right, were actually going to win the election, but were prevented from doing so by actions outside their control. They saw no reason Mitt Romney lost, they saw no reason Barack Obama was so popular, they saw no reason Todd Akin or Richard Mourdock lost, they saw no reason the House majority shrank, they saw no reason we didn't take back the Senate, and going forward they see no reason why we have to change to win next time. That means we will lose.