Sen. John Cornyn is declining to back Sen. Ted Cruz in his possible Senate primary in 2018. Cornyn, a member of the Senate Republican leadership, said he would endorse neither Cruz nor his potential primary challenger, Texas Rep. Michael McCaul. “I’m not going to get involved in any primary races particularly with my colleagues in the Senate,” Cornyn said. “We’ll see what happens, but we’ve got plenty to worry about between now and November 2016 before we start worrying about November 2018.” The unusual move highlights the rift between Cruz and his Senate colleagues, especially after the firebrand Texas senator declined to endorse Donald Trump for presdient during his speech at the Republican National Convention in July. Cornyn later said he saw “no benefit” in getting involved in a contested GOP primary.