After months of speculation about his political future, House Speaker Paul Ryan's office announced he will not be seeking re-election in 2018. He will, however, serve out the rest of his term.

He informed his GOP colleagues he was not running for re-election so he could spend more time with his three children -- their childhood is quickly ending, he said, and he wants to be a dad. Ryan received several ovations and many members shed tears, a source with direct knowledge told CBS News Chief White House correspondent Major Garrett.

Ryan addressed reporter's at the weekly House GOP conference on Wednesday, saying he was "proud of what this congress has achieved."

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"I think we've achieved a heck of a lot. We all know that I did not seek this job, I took it reluctantly but I have given this job everything that I have," Ryan said at the press conference. He added that he had "no regrets" for having accepted the responsibility of the speakership.

Ryan has been thinking about leaving the House for awhile, CBS News' Jenna Gibson reports, according to a source familiar with Ryan's thinking. The speaker will still want to help with the recruitment of new members, with fundraising and the ground game for the GOP.

On Tuesday night he made calls to extended family and a few close friends, CBS News' Arden Farhi reports. A handful of staff were also made aware Tuesday night. Wednesday morning he called the leadership team as well as the president and vice president and informed his staff before heading to the conference meeting.

Why is Paul Ryan Stepping Down?

Ryan cited being with his family, namely his children as reason for wanting to leave office. He said it's easy for the speaker role "to take over everything in your life and you can just let that happen, but there other things in life that are fleeting as well."

He added, "My kids will only have known me as a weekend dad, I just can't let that happen."

Ryan joins a growing list of Republican House members who are stepping away from Congress. More than 30 Republicans in the House and Senate have announced that they plan to leave Congress by the beginning of 2019.

The speakers's office released the following statement on Ryan early Wednesday morning:

"This morning Speaker Ryan shared with his colleagues that this will be his last year as a member of the House. He will serve out his full term, run through the tape, and then retire in January. After nearly twenty years in the House, the speaker is proud of all that has been accomplished and is ready to devote more of his time to being a husband and a father. While he did not seek the position, he told his colleagues that serving as speaker has been the professional honor of his life, and he thanked them for the trust they placed in him. He will discuss his decision at a press conference immediately following the member meeting." –Brendan Buck, Counselor to the Speaker

Senate Minority Leader Charles Schumer, D-New York, called Ryan "a good man who is always true to his word," and said that though they disagreed on most issues, "in the areas where we could work together I always found him to be smart, thoughtful, and straightforward." He also asked Ryan to reach across the aisle to Democrats during the remaining days of his term but noted that "the job may be made harder because Congressmen Scalise and McCarthy will be competing for the hard-right's favor." As Schumer noted, Representatives Steve Scalise, the majority whip, and Kevin McCarthy, the majority leader, are expected to compete for the speakership after Ryan's term ends.

President Trump issued a tweet on the news Wednesday morning, saying that will Ryan will not seek re-election, he leaves behind a "legacy of achievement that nobody can question."

Speaker Paul Ryan is a truly good man, and while he will not be seeking re-election, he will leave a legacy of achievement that nobody can question. We are with you Paul! — Donald J. Trump (@realDonaldTrump) April 11, 2018

Many speculated that Ryan would depart political office after helping successfully champion a rewrite of the U.S. tax code. Ryan's office, however, had denied the speculation that he was leaving anytime soon. The speaker previously told CBS News' "Face the Nation" in January that he would discuss running for reelection with his family before making a decision on the matter.

"Look, if we're doing fine I have no plans of going anywhere any time soon," Ryan said. "But that's something that my wife and I always decide in late spring of the election year."

In December of last year, White House press secretary Sarah Huckabee Sanders said President Donald Trump had called Ryan and the president made it clear he wouldn't be happy if Ryan quit Congress.

"The Speaker assured the president that those were not accurate reports and that they look forward to working together for a long time to come," Sanders said.

CBS News' Major Garrett, Jenna Gibson and Rebecca Kaplan contributed to this story.

This is a developing story and will be updated.