The Obama campaign is not trying to whittle away the numbers of Republican votes through a purging of voter rolls, as the GOP is trying to do to Democrats in Florida and Pennsylvania. But it is aiming to lower voting among the non-college educated white working class. Tom Edsall explains why:

Romney is particularly vulnerable to a campaign designed to suppress turnout because his support is more tepid than Obama’s. A New York Times/CBS poll released on Wednesday found that 52 percent of Obama voters back their candidate strongly, compared to 29 percent of Romney voters. In addition, a third of Romney’s voters say they are voting for him because of their dislike of Obama, while only 8 percent of Obama voters are primarily motivated by their hostility to Romney.

Vote suppression is important for Obama because his numbers among whites without degrees are worsening, despite the omnipresence of anti-Romney ads in the battleground states. Obama’s 29 percent level of support among non-college white men in the Quinnipiac poll cited above is a drop from 32 percent in its April survey, and the 28 percent level in the ABC/Washington Post poll is a drop from 34 percent in their May survey.

With his margins in this group falling, Obama directly benefits from every white non-college voter who stays home and does not vote for Romney.