The internal party vote to choose a successor for outgoing Speaker John A. Boehner (Ohio) took place behind closed doors in an afternoon meeting. According to a tally announced inside the room, Ryan won support from 200 of the 247-member GOP conference. A House floor vote to select the new speaker is set for Thursday morning, bringing an end to a five-week scramble to find Boehner’s replacement.

Thanking his fellow GOP members, Ryan called his nomination a “great honor” and said “this begins a new day in the House of Representatives.”

“Tomorrow, we are turning the page. We are not going to have a House that looks like it’s looked the last few years. We are going to move forward, we are going to unify. Our party lost its vision, and we are going to replace it with a vision,” Ryan said. “We think the country is headed in the wrong direction, and we have an obligation here in the people’s house to do the people’s business to heal this country.”

Ryan also singled out the outgoing speaker, saying, “John Boehner served with humility and distinction, and we owe him a debt of gratitude.”

Of Ryan’s nomination, Tom Cole of Oklahoma said, “I expected he would do very well, and he did.”

Bill Flores of Texas, Republican Study Committee chair, said he expected Ryan to lose no more than 20 votes on the floor Thursday. “That would show a united front,” he said.

“The only drama is going to be whether he loses 11 votes or 12,” said Rep. Glenn Grothman (R-Wis.) of Thursday’s floor vote.

Wednesday’s nomination vote comes hours before the House is set to vote on a controversial fiscal deal negotiated by Boehner that would increase government spending by $80 billion through September 2017 and raise the federal debt limit.

In a potential wrinkle to his recent effort to unify a divided House GOP, Ryan on Wednesday bucked pressure to oppose the deal from conservatives who worked to force Boehner from office, saying the agreement would help “wipe the slate clean” as he ascends to the top job.

Ryan, the 45-year-old chairman of the Ways and Means Committee, said in a statement that the deal has “some good, some bad, and some ugly” but will ultimately “go a long way toward relieving the uncertainty hanging over us.”

“It’s time for us to turn the page on the last few years and get to work on a bold agenda that we can take to the American people,” he said.

[Budget deal could end the fiscal wars until after the 2016 elections]

That announcement came a day after he told reporters that the process that led to the deal “stinks” and pledged to handle these kinds of major fiscal negotiations in a different way.

Most conservatives said earlier in the week they were sharply opposed to the budget deal but also said that they did not intend to hold it against Ryan. Many, however, said they would like Ryan to oppose the deal as a sign of good faith — even though Ryan had personally negotiated a very similar budget deal back in 2013.

But there were signs that they might look past Ryan’s policy positions if he makes good on his process-oriented promises.

Ryan on Tuesday endorsed a GOP conference review of existing rules and said he was committed to implementing changes by January: “It’s clear that members of the House and the American people have lost faith in how this place works. And naming a new speaker alone isn’t enough to fix it. We need a robust dialogue about improving the process so that each member has a greater voice, and we need a firm deadline to implement changes.”

Ryan has also made attempts to quell doubts about some of his policy positions that have left conservatives wary — mainly his past support for immigration reform legislation. In a Wednesday morning conference meeting, Ryan rose and pledged not to pursue any immigration bill unless it had the support of a majority of House Republicans.

White House officials — who have privately welcomed the prospect of Ryan’s elevation to speaker but have been cautious about embracing him publicly — said Wednesday they hope he pursues a different course after claiming the gavel.

“The president has worked with Chairman Ryan on some key issues, like trade and on immigration, but there are a number of issues where we have vastly different approaches, vastly different policy positions,” White House principal deputy press secretary Eric Schultz told reporters aboard Air Force Once. “Our concern all along in this process is that Republicans spend a lot of time and energy consolidating their fractious caucus, instead of working to figure out how Congress can run in a more bipartisan way.”

“We hope that that processes of identifying and selecting a new speaker isn’t a precursor to a partisan way of governing, but rather that the next speaker . . . is positioned to work with Democrats,” Schultz added.

Ryan faced one opponent, Rep. Daniel Webster (R-Fla.), who has gained a small but loyal following among hard-right lawmakers and fellow Floridians who have been drawn to his promises for reforming House rules and procedures.

[GOP hard-liners seek more power by changing rules. That could mean more chaos.]

But many of those who supported Webster when he was pitted against the previous presumptive nominee, Majority Leader Kevin McCarthy (R-Calif.), now say they are prepared to back Ryan after he reassured them over the past 10 days that he intends to move forward with many of the same reforms.

On Wednesday, Webster received 43 votes. Rep. Tim Huelskamp of Kansas, a Freedom Caucus member, said he was not surprised by Webster’s relatively strong showing but conceded that Ryan had enough votes to win the speakership Thursday.

He said the Freedom Caucus could take credit for forcing Ryan to abandon some of his demands for agreeing to serve as a speaker, including reforms to the rule allowing a majority of House members to vote out a sitting speaker.

Huelskamp declined to say how he intended to vote personally: “I think you’ll find out.”

Another Freedom Caucus member, Rep. Jeff Duncan (R-S.C.), who backs Ryan, said most of the 43 Webster backers had committed earlier to backing the Floridian and would be likely to back Ryan now that he has secured the nomination.

Ryan’s support for the budget deal, he added, may also have contributed to a protest vote: ‘I don’t think that helped him any.”

“If he gets 219 or 220, we have a brand new speaker,” Duncan said. “Regardless of what the vote is, he’s a guy who can unify the conference.

Wednesday’s meeting is the second time Republicans have gathered to choose Boehner’s replacement. An Oct. 8 meeting was abruptly cut short when McCarthy told colleagues he would not in fact seek the speaker’s chair in the face of determined opposition from hard-line conservatives.

[House Majority Leader Kevin McCarthy drops out of race for House speaker]

Rising to formally nominate Ryan on Wednesday was Rep. Trey Gowdy (R-S.C.), who enjoys a near-impeccable reputation among House conservatives that has been burnished in recent months by his leadership of a special committee investigating the 2012 attacks on U.S. officials in Benghazi, Libya.

Gowdy’s nomination speech, and Wednesday’s vote, took place in the same House hearing room where, a week ago, Gowdy and the Benghazi panel questioned former secretary of state Hillary Rodham Clinton for 11 hours.

Rep. Kristi L. Noem (R-S.D.) and Rep. Jeb Hensarling (R-Tex.), chairman of the Financial Services Committee, also spoke on Ryan’s behalf, a spokesman said.

Juliet Eilperin and Karoun Demirjian contributed to this article.