Reply #3: Historically, that has proven to be an accurate measure.

[FBaggins]

If anything (in midterms), it has been to our advantage.

but the majority of Obama's voters just started turning out in 2008

Nothing even close to the majority, but your point is still valid. Many Obama voters were first time voters.

It is, however, important to note that even their tightest LV screen still results in far more people counted as likely voters than actually turn up to vote. In this poll, it was 2/3rds of the registered voters polled... and midterms have been around 40% turnout in recent years.