Rick Perry
Perry has been mentioned as a possible challenger to U.S. Senator and fellow 2016 Republican presidential candidate Ted Cruz in 2018. Speculation about Cruz being challenged in the Republican primary arose during the 2016 Republican National Convention, when Cruz refused to endorse Donald Trump, the eventual Republican presidential nominee, whom Perry had endorsed after Cruz suspended his campaign. In a poll conducted from August 12 to 14 of that year by Public Policy Polling, Perry had a 46%-37% lead over Cruz. In November 2016, Perry declined to enter the senate race and endorsed Cruz in the elections.