As only 40% of American actually voted, and the almost 50/50 result suggests that approx. 20% of the population made a clear statement about supporting the POTUS and his party. Like wise, only 20% give or take supported the opposition. All the 60% who didn't vote either decided they couldn't be bothered to vote, couldn't, or too young.
Either way, your statement leaves me doubting it's veracity.
315,393,565 total population of the US
2012 Turnout : 126,838,980
126,838,980/315,393,565 x 100% = 40.2% of the population.