But once you get beyond those top candidates, what struck me was that Klobuchar was starting to creep up, having doubled her support since the last poll, to 6%. Looking at a broader measure, she was at just 2% in the RealClearPolitics’ average in Iowa as of late October and is now at 5%.

The reason why her recent jump is noteworthy is that the first initial move is often the hardest part. When a candidate is in the low single digits, it’s difficult to break out, because voters don’t want to waste their time or vote on somebody who they don’t think can win, even if they like that candidate.

But once that candidate starts breaking out a bit, they get more attention, and if they’re well-liked and a good fit for the electorate, they can start polling well enough to be considered “viable.” At that point, those who liked that candidate but didn’t want to waste their vote, start jumping on board — and the growth can be exponential.