Sen. Elizabeth Warren increased her advantage over former Vice President Joseph R. Biden across early states in the race for the 2020 Democratic presidential nomination, according to polling released on Sunday. Ms. Warren had a 31% to 25% edge over Mr. Biden among voters across 18 early primary and caucus states, up from a 1-point, 26% to 25% edge over Mr. Biden in surveys released last month, according to the CBS News polling. In New Hampshire, she led Mr. Biden by 8 points, 32% to 24%, up from a 1-point edge last month. Ms. Warren and Mr. Biden were also...