There is a lot of anger toward Trump in areas around Democratic cities, per WashPost: "If Republicans want to hold onto the House, they will have to compete in communities that had little to do with the working-class regions that sent Trump to the White House in 2016: affluent, white-collar suburbs of Democratic cities."

Why it matters: "Many of the most competitive House seats this year are in the tony bedroom communities of Los Angeles, Chicago, Denver, Houston, Philadelphia, New York and Washington."

The catch-22 for Republican candidates, per N.Y. Times' Jonathan Martin and Alex Burns:

"If they stay faithful to Mr. Trump they risk incurring the wrath of many in the political center during the general election, likely dooming their campaigns. But if they disavow the president, they risk depressing turnout from their core Republican voters and watching their pool of volunteers evaporate overnight."