Texas voters will see something they've rarely seen this century thanks to Attorney General Ken Paxton. When the Republican announced last week that he would run for the U.S. Senate, it set the stage for just the third open-seat battle for the attorney general's office since the year 2000.

Texas Attorney General Ken Paxton's entry into the U.S. Senate race against incumbent John Cornyn could serve as a litmus test for a Republican party in flux. "It's an establishment versus an insurgent campaign,