Cook Political Report: “With 102 days to go, Democrats remain substantial favorites for House control. A big reason: Republicans are defending 42 open or vacant seats, a record since at least 1930.”

“Of Republicans’ 42 incumbent-less seats, eight are in districts that voted for Hillary Clinton in 2016, and an additional 13 are in districts where President Trump received less than 55 percent. History is working against the GOP in many of those seats: we found that since 1992, in situations when a president’s party was stuck defending an open seat two years after the president failed to carry it, that party has batted zero for 23 keeping it in their column.”

“In a wave environment, 42 seats is a dangerous level of exposure: If Democrats win even eight of the 42 (our current ratings pin eight as Lean/Likely Democratic and four more as Toss Ups), they’ll already be over a third of the way to a majority.”