Could non-citizen voters sway U.S. elections?

Soak in this one. It's from the Washington Post:

How many non-citizens participate in U.S. elections? More than 14 percent of non-citizens in both the 2008 and 2010 samples indicated that they were registered to vote. Furthermore, some of these non-citizens voted. Our best guess, based upon extrapolations from the portion of the sample with a verified vote, is that 6.4 percent of non-citizens voted in 2008 and 2.2 percent of non-citizens voted in 2010.

Here's the rub, the story in the Post goes on to say many of these apparent illegal voters don't know they're doing anything wrong. They don't know enough about our country, our customs, or our laws to know non-citizens can't vote.

The Post also concedes, when illegals vote, they tend to vote Democrat.