Defeating any incumbent president is serious, difficult and expensive business, especially w a president coddled and protected by the MSM. Since 1900, only 4 presidents were denied re-election, three of whom were primaried. (Excluding Ford since he was never elected in his own right). Moreover, of the 4 defeated incumbents, only one was a Dem, Carter.
The race was this: Romney ran better than his campaign. Obama’s campaign ran much better than Obama.
They had a 4-yr invisible army that was missed or dismissed.
And they’ll always have an advantage: send a bus to a housing project and it will bring a bus load of Dem voters to the polls.
R’s will never match that efficiency.