Presidential primary debates can make — and break — a campaign

In the 2012 presidential election, then-Texas Gov. Rick Perry entered the GOP primary race in mid-August 2011 and quickly jumped into the lead ahead of Mitt Romney, the eventual Republican nominee. Then Perry botched an answer regarding a Texas policy for illegal immigrants in a September 2011 primary debate that alienated the GOP base. His numbers plummeted, just in time for him to have his infamous “Oops” moment in a November 2011 debate, when he forgot the third of the three federal agencies he wanted to eliminate as president. Perry did poorly in the early primary contests and then dropped out in January 2012. In the 2016 campaign, then-Wisconsin Gov. Scott Walker entered the Republican field seemingly as one of the front-runners. But Walker made a number of mistakes in his campaign, including an early pair of forgettable debate performances that put his campaign on life support as donors ran away, and he ended his campaign in late September 2011.

Below we’ve plotted Perry’s 2012 GOP primary poll performance using FiveThirtyEight’s database of polls,2 annotating the timing of the key debate events described above. It’s not hard to see how quickly Perry’s polling numbers fell following his debate comments on immigration policy, and how they were already very much in decline by the time he said “Oops.”