(CNN) Speaker Paul Ryan's decision not to seek an 11th term this fall sends a chilling signal to Republicans hoping to keep control of the House in November while also illustrating the impossibilities of serving as an elected GOP leader in Donald Trump's Washington.

"This morning Speaker Ryan shared with his colleagues that this will be his last year as a member of the House," confirmed Ryan spokeswoman AshLee Strong. "He will serve out his full term, run through the tape, and then retire in January."

Ryan had been hinting behind-the-scenes for months that he wasn't going to be around all that much longer. Remember that he was cajoled into taking the job in 2015 following then-Speaker John Boehner's resignation amid pressure from conservatives inside and out of Congress. Ryan initially blanched at taking the job but stepped forward when it became apparent that there was simply no one else who could win a majority of the majority's vote.

Nonetheless, his retirement will send shockwaves through a party already reeling in the face of what looks to be a growing Democratic wave headed its way in a few months time. Ryan is the 40th Republican to announce a decision not to seek reelection as compared to just 19 for Democrats.

While Ryan's seat isn't ultra-competitive -- Trump won it by 10 points -- his decision not run could well set off a slew of retirements from GOP members who had been wavering about whether to run again in what looks to be a very, very difficult national environment. ( There are still 19 states where the filing deadlines haven't passed -- including New York where filing closes on Thursday.)

"It may encourage other Republicans to not run again, I think moreso than affecting the money," Rep. Tom Massie, a Kentucky Republican, told CNN's Juana Summers. "We've already got twice as many retirements in our party as the Democrats. This may be a signal that it's OK to retire."

No matter what Ryan says about his retirement having everything to do with his personal life and nothing to do with the political winds, the simple fact is this: Speakers of the House don't retire from the job when everything is going great for their side. Odds were that Ryan would find himself as House Minority Leader when the dust cleared this November. And he didn't want that. Of course, by announcing his retirement, Ryan just made it even more likely Republicans lose the House.

While there's no doubt that the prospect of losing control of the House factored into Ryan's decision as did his personal life, the largest factor was the one sitting in the White House.

Ryan's relationship with Trump was fraught from the start. The speaker, as titular head of the Republican party, was forced to react to every untruth, exaggeration and attack leveled by the real estate magnate during the course of the 2016 campaign. After a series of attempts to distance himself -- and the GOP in Congress -- from the party's presidential nominee, Ryan cut ties entirely in early October.

"The speaker is going to spend the next month focused entirely on protecting our congressional majorities," said Strong at the time, while, behind the scenes, Ryan allies insisted he was done defending Trump in any way, shape or form

Then, Trump won.

As surprising as that result was to Ryan, he also saw an opening. Trump was as surprised as anyone about his victory. And, he had no real policy plans or idea how to accomplish them. Enter Ryan, the ideas guy of the Republican party! (For much more on all of this, check out PBS Frontline's " Trump's Takeover. ")

The problem for Ryan was that Trump wasn't willing to simply follow the blueprint the House Speaker laid out for him.

Plans to quickly repeal and replace the Affordable Care Act faltered amid the lack of any sort of consensus among Republicans as to what the party should replace Obamacare with. That slow-motion failure -- the House passed a repeal and replace measure, the Senate did not -- led to a break in Trump's trust relationship with Ryan and the rest of the GOP congressional leadership.

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You told me this all would be easy and it's not, seemed to be Trump's prevailing thought. And, once he started to distrust what congressional Republicans were doing -- and what they could deliver -- things went downhill from there.

Yes, the party managed to pass a major tax cut bill -- a giant accomplishment for Ryan who has long wanted to lead a tax reform push -- but it was one piece of gold amid the dross.

The latest provocation? Trump threatened to veto the omnibus spending bill last month , insisting it didn't do enough about funding the border wall. That veto threat, which Trump eventually backed away from, stunned congressional Republicans who had already left Washington patting each other on the backs for keeping the government open and funded

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The reality for Ryan was -- and is -- this: He had hoped that the election of Trump would be a seminal moment for the rise of his ideas on taxes, deficit reduction and everything else under the sun. While he got the tax cuts he has long coveted, it became clear over the past 15 months that Trump simply didn't see the world the same way that Ryan did.

And not just that: It also became clear that the rank and file in the Republican party -- inside and outside of Congress -- were more aligned with Trump's vision of the party and the country than Ryan's.

With Trump showing no signs of changing his political approach, the party headed for what looks like be a cataclysm this fall and with his three kids entering their teen years, the time was ripe (and right) for Ryan to step aside.

It seems very unlikely, however, that Ryan has left the political stage forever. Ryan is only 48 years old. He quite clearly has national political ambitions, and it's possible that those ambitions are best served by getting out of Dodge now and waiting until the Trump era passes -- whether in 2020 or 2024 (when Ryan will only be in his his 50s).

Ryan will live to fight another day. But make no mistake: His vision of the GOP has taken a backseat to Trump's.