Paul Ryan declares his candidacy for House speaker | McClatchy Washington Bureau

Rep. Paul Ryan said Thursday that he’ll run for speaker of the House of Representatives after securing support from conservative and centrist Republican groups in the lower chamber.

Ryan, R-Wis., made the announcement in a letter to House colleagues late Thursday, declaring "I am ready and eager to be our speaker."

"I never thought I’d be speaker," Ryan wrote. "But I pledged to you that if I could be a unifying figure, then I would serve – I would go all in. After talking with so many of you, and hearing your words of encouragement, I believe we are ready to move forward as one, united team."

Ryan’s announcement came hours after he received the backing of the Republican Study Committee, a 170-member conservative group within the 247-member House GOP conference, and the so-called Tuesday group, a centrist Republican body.

"After hearing Paul lay out his vision for the future of the Republican conference, I am confident that he is the right person to lead the House going forward," said Rep. Bill Flores, R-Texas, the study committee’s chairman. "He has the policy expertise, conservative principles and strong values we need in our next speaker. He is a member of the Republican Study Committee and has shown he is willing to work with fellow conservatives to address our policy and process goals."

Flores said the study committee’s 17-member steering committee "overwhelmingly" voted to endorse Ryan after the House Ways and Means chairman met with the entire group Wednesday. The endorsement from the moderate Tuesday group came as no surprise.

"I appreciate the support of the Tuesday Group," Ryan said in a statement Thursday. "This is one more step toward building a united Republican team."

Ryan’s bid for speaker received its biggest boost Wednesday night when a strong majority of the House Freedom Caucus, which has about 40 members, voted to support him.

Party unity was one of the conditions that Ryan demanded of House Republicans for him to agree to run to replace John Boehner as House speaker. He also called for changes in a procedure called the motion to vacate the chair – a maneuver that enables a lawmaker to try to oust a speaker – and a break from a heavy travel schedule in order to spend time with his family in Wisconsin on weekends.

Ryan had given his Republican colleagues until Friday to decide whether they agree to his terms. If they didn’t Ryan said he would be happy to remain Ways and Means chairman. Boehner, R-Ohio, has set Oct. 28 for the House Republican conference to choose its nominee for speaker and Oct. 29 for the full House to vote for the next speaker.

White House Spokesman Eric Schultz said Thursday that President Barack Obama “believes that Congressman Ryan is someone who has given considerable thought to the significant issues that must be worked through in Congress. On some of those issues, he has worked with the president and with Democrats, like on trade and immigration. But on others, we have vastly different approaches.”