[WS:] This is my impression too. However, I would like to add an important caveat - selective mobilization of non-voters can have a significant impact on election outcomes, especially in a duopolistic system in which the electorate is more or less equally divided (such as in the US.) Selective mobilization of non-voters can easily tip this balance in favor of those who are more effective in that mobilization.
Both parties seem to understand and use this by appealing to different fractions of non-voters - Repugs to the looney wingnuts, racists, conspiracists, love-my-country-but-cannot-pay-my-bills jingoists and what not that are dime a dozen among the lumpen and Democrats to the "bread and butter" sentiments of the working class. I think that the Repugs are more successful due to the sheer bombast they use. Dems do not have that many salient bread and butter hot buttons anyway outside the Obamacare which seems to be more of a liability than an asset. So at this historical moment, mobilizing non-voters is likely to have a reactionary rather than a progressive effect. This of course could change if Dems came out with a strong progressive message, but it is unlikely to happen due to the "shadow cast on the US politics by big business."
Wojtek