At the white-tie Al Smith dinner in New York on Thursday night—an annual affair at which speakers traditionally roast high-profile politicians—House Speaker Paul Ryan engaged in a bit of self-deprecation in between several swipes at Donald Trump. “Every afternoon, former Speaker John Boehner calls me up. Not to give advice. Just to laugh,” the Wisconsin lawmaker said in reference to his predecessor, who resigned from Congress in 2015 and has spent his time since sipping merlot and throwing shade. Though the remark was in jest, it reflects the unsettling reality that a number of Ryan's closest allies in the Republican caucus are abandoning ship. On Thursday, Pat Tiberi of Ohio announced his plans to resign from Congress by the end of January and enter the private sector. The departure of Tiberi, a member of the House Ways and Means Committee, comes as a blow to Ryan and the rest of House G.O.P. leadership, who intended to tap the lawmaker to lead the powerful tax panel in the near future, according to sources that spoke with Politico.

The exodus of Republican lawmakers continues to grow. Tiberi joins the ranks of Dave Trott of Michigan, Charlie Dent of Pennsylvania, Ileana Ros-Lehtinen of Florida, Dave Reichert of Washington, John J. Duncan Jr. of Tennessee, Lynn Jenkins of Kansas, and Sam Johnson of Texas, all of whom announced their retirements earlier this year. Tim Murphy—another Ryan ally—was recently forced out of Congress following a sex scandal. Then there's the slate of Republicans seeking higher office: Congressmen Luke Messer and Todd Rokita are both running for Indiana Senate seats, and Kristi Noem of South Dakota and Jim Renacci of Ohio are mulling gubernatorial races. One senior Republican noted to Politico that the trend was roughly in keeping with the rate of departures at this juncture in previous Congresses. But beyond the numbers, House sources emphasized that the majority of members leaving are “more seasoned lawmakers who ‘row with the team’ as Ryan likes to say,” which makes their exits more significant.

While Tiberi ostensibly decided to leave Congress for both personal and professional reasons, his decision accentuates a broader pattern of prominent Republican lawmakers leaving office or retiring amid growing frustrations at the Republican Party’s lack of legislative accomplishments—despite its control of both houses of Congress and the White House—and the near-daily chaos caused by a volatile Republican president. “This is a harder life in terms of being away from home and putting up with the pace and the public battering that one sometimes must endure,” Representative Tom Cole of Oklahoma, told The New York Times. One recently departed G.O.P. congressional aide echoed the sentiment to Politico: “The job isn't fun anymore. You get beat up in D.C. for everything Trump says or does, only to go home to get beat up for not defending Trump enough by the base. It's brutal.”

Much of the blame for Congress’s failure to deliver on key legislative promises has fallen on the shoulders of Ryan and his upper-chamber counterpart, Mitch McConnell. And as the list of lawmakers throwing in the towel gets longer, the G.O.P. leadership’s role is destined to get more complicated—particularly if Steve Bannon succeeds in his war against the Republican establishment. In recent weeks, however, a number of Republicans have expressed not only frustration with their ranks, but with the president. “It’s very difficult to achieve big-ticket items, not to mention just accomplish the basic items of governance—keeping the government open or not defaulting on our obligations—so that’s a source of frustration for me,” Dent told Politico, adding, “Congress should take a lot of the blame; but so should the president. The president doesn’t lay down his plans, his ideas, his policies, and he sure as hell didn’t try to sell it to the American people on health care—and that’s a function of leadership. Saying, ‘Send me a bill and I’ll sign it'—that’s not leadership.”

Arguably, lawmakers seeking re-election in 2018 will be judged according to Trump's achievements as much as their own. “Donald Trump is the Republican Party . . . he will be probably as long as we can keep talking about him because they allowed him to happen, and they need to own it,” Jeremy Bird, who served as Barack Obama’s national field director in his 2012 re-election campaign, told me. “We are running against Trump no matter what because the Republican Party is in bed with him, and their leadership is supporting him, and no one is really standing up to him.” And considering Trump's flagging approval ratings, it makes sense that G.O.P. lawmakers would choose to avoid what could be permanently bruising re-election campaigns. As multiple sources told Poiltico, Tiberi “will hardly be the last to leave.”