Beto O'Rourke stormed into the presidential race arguing his experience growing up along the southern border and a relatively moderate approach to politics would distinguish him in a crowded field. Pete Buttigieg, the 37-year-old mayor of South Bend, Indiana, has become a top-tier White House hopeful with an earnest, intellectual and largely moderate appeal. The other Texan in the race, former Obama housing secretary Julián Castro, has overshadowed O'Rourke on immigration issues, scolding him during last month's debate for not being willing to fully decriminalize crossing the U.S.-Mexico border illegally.