I had a conversation with a source in the Cruz camp, who spoke on background. Their latest poll, with which the source was familiar, was taken on Sunday night, and showed Cruz with a double-digit lead and everything trending in Cruz’s direction.

The Cruz campaign polled only people who had actually voted in the May 29 primary. They did not poll Republicans who did not vote in the primary. “We’re missing that universe,” the pollster acknowledged. “We only wanted 2012 primary voters.” Here was his crucial point: Based upon the numbers in the internal poll released by the Dewhurst campaign, Dewhurst would have to get 90% of the “missing universe” to win the election. And that defies the law of probability. 

The pollster said that after the primary, nothing was moving for either candidate for three weeks. From late June until early voting for the runoff, the race was static. The TV ad war did not move votes. The debates did not move votes. The race was  close until the Wednesday night before the runoff. That was when the Cruz camp saw that voters were becoming more attentive, and the electorate started breaking for Cruz, and the momentum was all in his direction.