Adding up the male and female vote in 2008 gives us a total of 130 million votes. According to Harper's, there is a pool of 90 to 95 million voters who are staying out of the voting process and that about two-thirds of that number would vote for a Democratic candidate if they were compelled to cast a vote (The piece recommends extremely mild, slap-on-the-wrist penalties for not voting). The first piece adds that part of the reason Obama won in 2008 was that "Turnout among young black voters was 55%, eight percentage points higher than four years earlier," and that "turnout among blacks, Hispanics and Asians increased by four percentage points in 2008 from four years earlier."
So why do the Presidency, the House and the Senate all skew to the
right wing politically more than demographics suggest they should be
doing? Why aren't they all pandering and competing more towards the
left side of the political spectrum? Two reasons, the first is campaign
finance. Campaigns need money to get out their message and to air
advertisements and getting a big check from a wealthy person is a good
deal easier than getting lots of small checks from a lot of voters. A
quick Google search on "obama small donors" shows that Obama did better
with small donors in February 2012, but that he now gets about the same
percentage of big to small donors as his Republican rival does. The
second reason is that many on the left/liberal/progressive side of the
aisle are convinced that the system is corrupt.
What's the result of people boycotting the system? Commenters saying that "we live in a center-right country,"
even though polling on specific issues (budget/economy) shows that voters lean towards the left on most political issues. Counting up newspaper
endorsements, Romney has more newspapers endorsing him than Obama does,
but "Total circulation of the newspapers endorsing Obama: 12.8 million Total for Romney: 7.8 million." [emphasis in original] But the vote is far closer than it should be.
Essentially, boycotting the vote because it's corrupt is of great electoral benefit to the right wing and helps get right-wing politicians into office.