Ryan, R-Wis., told colleagues Wednesday that he will not seek reelection this year, ending a almost 20-year tenure in Congress and adding further uncertainty about whether embattled Republicans can maintain control of the House.
"This morning Speaker Ryan shared with his colleagues that this will be his previous year as a member of the House", Brendan Buck said.
Rumors of Ryan's retirement became circulating at the end of past year. "He will serve out his full term, run through the tape, and then retire in January", Buck said in the statement.
Brendan Buck, counselor to the speaker, says the "the speaker is proud of all that has been accomplished".More news: Facebook data leak impacted 87 million users
Rumours that Ryan would consider leaving office after the 2018 midterms had been circulating for some time, and the Speaker himself said back in January that re-election was a decision that both he and his wife were planning to make in late spring.
Ryan is expected to address his future intents in a closed-door conference with the GOP later this morning.
The party has seen a large number of retirements, and Ryan's exit is certain to sap morale as Republicans seek to contain a surge in enthusiasm from Democrats, whose fortunes have been buoyed by the unpopularity of President Donald Trump.
Top contenders to replace him are McCarthy and Senate majority leader Steve Scalise.
"Speaker Ryan has served our country well for decades as a thoughtful policy leader in the House", he told CNN.