Ironically, O'Rourke could ask Cruz about this problem. He arrived in the Senate and immediately laid the groundwork for a presidential campaign that saw him finish second to Trump in the 2016 primary. Cruz then alienated much of his base by refusing to endorse Trump at that year's Republican National Convention, and though he's since embraced the president, some Texas conservatives say they're still wary, seeing what happened at the convention as putting personal ambition over party.