"The Foundation of Trump's Coalition Is Cracking"

"Although changes in survey methodology may partly explain the difference, the 2018 exit polls showed that among both working-class white men and women who are not evangelicals, Democratic House candidates won a measurably higher share of the vote than Hillary Clinton did in the 2016 presidential race. In the heavily blue-collar Rust Belt states that tipped the 2016 election to Trump—particularly Michigan, Wisconsin and Pennsylvania—even small improvements might be enough to tilt the result the other way."

Ronald Brownstein at CNN points to an intriguing difference among white voters.