You read the pre-post-mortems on the midterm elections today and you see a clear set of frustrations bubble to the surface. Young voters are mad that their concerns and perspective has not been addressed in the first two years of the Obama presidency. Voters in the Midwest look around their bleak economic landscape and cast about to blame the party in power. Even attendees at the Rally to Restore Sanity And/Or Fear, largely Democratic, shook their head at their political leaders “running for cover,” and feeling that “We don’t have any place to turn.”

There’s truth in all of this, especially as it speaks to real-world frustrations that Americans feel every day. But the pre-post-mortem of this election season has to include something that Democrats should have known the day after the 2008 election – that coalition they built to give the Presidency to Barack Obama does not typically turn out in a midterm. This fundamental problem – a coalition that is necessarily smaller in a non-Presidential year – speaks to almost the entire problem Democrats will have at the polls tomorrow.

According to an analysis by the Pew Research Center for the People & the Press, there likely will be more non-voters this year than voters. Indeed, turnout in midterm elections typically is less than 40% of the voting-age population.

The survey shows that those who choose not to exercise their franchise likely will be younger, less educated and more financially stressed than those who call themselves likely voters.

And, not surprisingly, those who choose not to vote could be considered more liberal than those who do, reinforcing the conventional political wisdom that the American electorate is right of center, and successful politicians are those who move to where the voters are.

Non-voters are far less likely to call themselves conservative. They are far more likely to support an activist government. They oppose same-sex marriage in smaller numbers.

Part of this is that Republicans have flipped so much of their electorate from non-voters to voters just through the intensity of their pitch this year. But a lot of this is structural. I wrote about the “Rising American Electorate” and drop-off voters in my first month at FDL News. The RAE includes unmarried women, young voters and nonwhites. In that post, Page Gardner of Women’s Voices Women Vote told me that “drop-off voters among RAE populations could mean a loss of 140,000 votes in Nevada, 200,000 votes in Missouri, 900,000 votes in Florida and 2 million votes in California.”

That’s basically the election right there. It was going to take a lot to get these voters to turn out in a midterm, and one thing they certainly needed as an incentive is the impression that their vote in 2008 meant they achieved some tangible success in their lives. That mostly didn’t happen, and tomorrow we’ll see the results.