Getty Images/Illustration by Emily Bogle/NPR

It was a tight race, so a campaign staffer doubted the results of an unreleased poll showing their candidate up — by a lot.

The tip about the outside poll didn't match up with the campaign's internal numbers. But accuracy aside, the staffer knew the poll would shake up the prediction markets . One market had their candidate down by double digits.

"Myself and others started placing bets before that poll came out," the staffer, who was working on a statewide campaign in the South, told NPR on the condition of anonymity over fear for their future employment.…