Rep. Patrick J. Tiberi (R-Ohio), will retire at the end of January. (John Minchillo/AP)

Rep. Patrick J. Tiberi (R-Ohio), a member of the House Ways and Means Committee, announced Thursday that he would leave Congress early next year to enter the private sector, jolting GOP leaders as they scramble to pass legislation to rewrite the U.S. tax code — one of President Trump's signature campaign promises.

Tiberi's decision underscores the mounting challenge facing House Speaker Paul D. Ryan (R-Wis.) in retaining veteran Republican lawmakers, many of whom have grown weary of the tumult and stumbles that have come to define the Trump era on Capitol Hill.

"It is with a humble and thankful heart that I will not be seeking reelection," Tiberi said in a statement. "While I have not yet determined a final resignation date, I will be leaving Congress by January 31, 2018."

Tiberi, 54, said he has accepted an offer to lead the Ohio Business Roundtable, a business advocacy group in Columbus.

Tiberi's decision to leave the House before the end of his term, which surprised colleagues and Ohio Republicans, is another rupture in the ongoing deliberations among congressional Republicans over tax policy.

As a senior member of the House's tax-writing committee, Tiberi is positioned to exert significant influence over his party's tax overhaul, especially since its specific provisions are largely unwritten. But his willingness to leave the House by late January, perhaps amid an intense GOP push on taxes, raised questions about its fate.

"Tax reform was do or die before Pat's decision to leave, and certainly is now," said former Minnesota congressman Vin Weber, who is close to Republican leaders. "His departure isn't helpful. He's a good guy, a smart guy."

Others in the GOP orbit said Tiberi is a major player but not central to the chances of tax legislation.

"I actually feel more optimistic today than I did two weeks ago," said Heritage Foundation senior fellow Stephen Moore, referring to the GOP's movement toward passing a budget this week, which includes instructions for the expected tax legislation.

"It's going to be a heavy lift, for sure, when you take on the swamp creatures. But in the end, Republicans finally get the consequences of not passing tax reform would be catastrophic for the party, and they could be wiped out in 2018," Moore said.

The Ohio congressman joins a growing crowd of leadership-friendly Republicans who are leaving Congress. Reps. David Reichert (R-Wash.), Charlie Dent (R-Pa.) and David Trott (R-Mich.), among others, have already announced they will not seek reelection.

Dent said in an interview that more mainstream Republicans may do the same later this year, driven by their unease with the chaotic political environment in Washington.

"Do I think there will be more? Yes. Am I prepared to say it'll be an avalanche? No. But I do think there will be more retirements," Dent said. "Since Trump, we spend much of our time now just responding to the tweet of the day or the latest outrage. It's really distracting from accomplishing our legislative agenda."

Dent added: "Do you really want to spend next year explaining what's going on here? I know I don't."

Tiberi was elected to the House in 2000 after working as a real estate agent and serving in Ohio's state legislature. The New York Times first reported his decision to step down.

According to two friends of Tiberi, who requested anonymity to speak candidly, the Ohioan was motivated to leave by his desire to spend more time with his wife and four daughters, make more money, and escape the daily drama of Congress.

Tiberi has also voiced private frustrations about his political future, following a failed bid to chair the Ways and Means Committee in 2015 and flirtations this year with a run for statewide office next year that have not panned out, even though the congressman has more than $6 million in his campaign account, the friends said.

Tiberi's seat — in Ohio's 12th Congressional District — is in central Ohio and includes suburban communities near Columbus. Seen as reliably Republican, it was once held by Ohio Gov. John Kasich (R) and has not been held by a Democrat in decades. Many local GOP figures said Thursday that they would probably seek the party's nomination.

Meredith Kelly, a spokeswoman for the Democratic Congressional Campaign Committee, said Democrats "will be in the fight" if party leaders decide "this district gets us closer to that goal" of retaking the House majority.

During Ohio Republican John A. Boehner's tenure as House speaker, Tiberi was well known at the Capitol as a trusted friend and one of his lieutenants. At times, when members wanted to get a message to Boehner, they huddled with Tiberi.

Ryan, too, sees Tiberi as an ally.

"Patrick J. Tiberi has brought great decency and relentless passion to this House," Ryan said in a statement. "For me, personally, Pat is a dear friend whose thoughtfulness I cherish."