So now it seems Hillary and Obama are tied for the lead in one Democratic primary poll. Pretty remarkable considering she had a 17 point lead last time out and a 12 point lead last week in another poll. Even if the 17 point poll and the even poll are at the edge of their margins of error, that is still a huge swing.
So what gives? USA Today's story makes the leap that Obama's messages are "starting to stick." Andrew Sullivan says that Obama clearly has more cross-over appeal. They both might be right, but then they might not. Polls have been strangely unreliable over the last handful of years, and (this is admittedly anecdotal) and large swings seem more prevalent.
It sure seems like there are some external validity issues within these polls. True random sampling seems like the most likely culprit. Admittedly, I don't know exactly how these tests are conducted, but someone with more time than me should look into this.
On the other hand, the widespread opinion is that Hillary has been winning the debates. Ask John Kerry what winning debates did for his electability.