The Speaker of the House, Republican Paul Ryan of Wisconsin announced Wednesday he would not seek re-election in 2018. He is the 38th*, and most prominent member of the GOP to retire rather than face the voters in an election that may lead to a Democratic House majority in 2019. The New York Times suggests that "it could also trigger another wave of retirements among Republicans... taking their cue from Mr. Ryan."
While not likely a major factor in his decision, Ryan was facing a more challenging race to hold his district than the one he won by 35% in 2016. With his departure, Sabato's Crystal Ball moves the race from 'Likely Republican' to 'Toss-up'. The GOP has until June 1st to find a suitable replacement for Ryan on the ballot -- the only other Republican on the ballot at present is white nationalist Paul Nehlen.