Nate Cohn: “While it’s tempting to be skeptical, a blue Texas is increasingly easy to imagine. It’s even easier to imagine after Ken Paxton’s victory over John Cornyn, the incumbent senator, in the Republican primary runoff on Tuesday night.”“That’s partly because Mr. Paxton, the state attorney general, has distinct political liabilities. He’s faced investigation, indictment, impeachment and a messy public divorce.”“But there’s another reason Democrats might pull off a statewide win for the first time in three decades: demographics. Texas is one of the most diverse states in the country, and national polls show Democrats surging back in support among young and nonwhite voters — and especially Hispanic voters.”