Speaker Paul Ryan's announcement that he will not seek reelection to his southeastern Wisconsin district in 2018 (though he will serve out the rest of his term) is a deep blow to his party's morale in its uphill efforts to hold the House majority. It's also not entirely a surprise: when he reluctantly took the speaker's gavel in 2015 under heavy pressure, he couldn't have imagined he would have to deal with a President Donald Trump.

Nearly two years after Ryan initially refused to endorse Trump as the nominee, Trump's takeover of the GOP base is nearly complete. Ryan and Trump forged passage of a signature legislative initiative—tax cuts—but overall, Trump's populist vision for the party has supplanted Ryan's supply-side conservatism. Last week's YouGov poll found Trump's favorability with GOP voters at 80 percent; Ryan's was just 52 percent.

Several Ryan confidants had speculated that he would run for reelection and quit the speakership in December or January, sparing his conference the appearance of "folding" the majority before the election. But his early lame duck status could hamper the ability of his PAC, the Congressional Leadership Fund, to raise money to defend other GOP incumbents badly in need of air cover.

It also means NRCC Chair Rep. Steve Stivers's drive to defend 240 GOP seats this fall could be overshadowed by internal jockeying between Majority Leader Kevin McCarthy and Majority Whip Steve Scalise for a speakership that may not exist come January. As of today, there are still 19 states where filing deadlines haven't passed, home to 58 GOP members who are currently running for reelection but still could retire.

More locally, Ryan's exit puts his southeastern Wisconsin seat at risk for the first time since his initial election in 1998. Wisconsin's 1st CD is a traditionally Republican seat: it voted for Trump 52 percent to 42 percent in 2016 and for the Mitt Romney/Paul Ryan ticket 52 percent to 47 percent in 2012. Last Tuesday, a GOP-backed state supreme court nominee carried the 1st CD by five points despite losing statewide.

But now, Republicans will have to start from scratch without Ryan's $9.6 million campaign account against a Democrat armed with millions and a blue-collar profile.

Democratic Army veteran and former ironworker Randy Bryce, perhaps better known as the "Iron Stache," has been a national phenomenon on MSNBC and in left-leaning online fundraising circles for months. He ended March with $2.3 million on hand and will have a massive financial head start over the GOP field. But he also sports serious personal liabilities, including late child support payments.

Ryan's camp insists the race against Bryce had nothing to do with his decision. A source close to Ryan shared with the Cook Political Report an internal campaign poll taken in March by Public Opinion Strategies showing Ryan leading Bryce 55 percent to 34 percent and Republicans ahead 48 percent to 36 on the generic ballot in the 1st CD. Democrats view that as an overly rosy portrayal.

Wisconsin's candidate filing deadline is June 1. Republicans have a deep bench here, and potential GOP candidates include state Assembly Speaker Robin Vos, state Sens. Van Wangaard and Steve Nass and UW Board of Regent member Bryan Steil. A top GOP priority will be ensuring that openly anti-Semitic activist Paul Nehlen, who received 16 percent against Ryan in the 2016 primary, doesn't win the August primary.

Ryan's retirement shifts Wisconsin's 1st CD from the Solid Republican column to the Lean Republican, with the potential for the race to become even more competitive.