The House Intelligence Committee will vote Thursday to approve a Republican-drafted report that aims to be Congress’s first official word on just what Russia and the Trump campaign did during the 2016 presidential election, a document expected to further complicate what’s become a contentious relationship among the lawmakers who have conducted the investigation.

Over the past year, the demand for a detailed, public assessment of Russian interference and the allegations of collusion surrounding President Trump has inspired three congressional panels to examine the actions of Trump’s affiliates during and after the election. But where others have mounted a bipartisan effort, the House Intelligence Committee has fractured along party lines, earning a reputation more for sniping than as a voice of investigative authority.

The GOP report, whose public release remains weeks away pending redactions from the U.S. intelligence community, has come to represent the deeply partisan divisions that have overtaken the probe. The panel’s ranking Democrat, Rep. Adam B. Schiff (Calif.), has already denounced the document, which concludes the Republicans found no evidence of collusion and criticizes the U.S. intelligence community’s assessment that Russia sought to help Trump. Democrats have pledged to press on with the investigation alone — but Republicans say they are planning to move on to other matters, including new probes of alleged anti-Trump activities at federal law enforcement agencies and the State Department.

“We just follow the facts, and we found no collusion,” said Rep. K. Michael Conaway (R-Tex.), who was deputized to run the probe last year when an ethics inquiry forced the panel’s chairman, Rep. Devin Nunes (R-Calif.), to step aside. “The report will make some people mad and will make some people happy, and so that’s where we’re at,” Conaway said.

With panel Republicans and Democrats focused on separate objectives for the next several months, some fear the political division could infect the committee’s other work. Already, the Russia investigation has caused many members to stop speaking to each other outside business meetings, while members of the intelligence community have expressed their frustrations with Nunes and the panel as a whole, according to people familiar with the dynamic

“What’s happening now I’ve never seen before,” said retired Gen. Michael Hayden, director of the National Security Agency under presidents Clinton and George W. Bush, and director of the CIA under presidents Bush and Obama. “What’s happening now is that many members of the president’s party on the committee are aligned with the president to make war on the president’s own security establishments . . . . It’s taken the partisanship to a place it’s never been.”

From investigations into the 9/11 attacks to the terrorist assault on a U.S. diplomatic compound in Benghazi, Libya, the House Intelligence Committee has grappled with politically divisive probes in the past. But current and former members of both parties say that Trump has riven the panel as no other matter has in decades.

“We lost our bipartisanship on November 9,” Rep. Chris Stewart (R-Utah) said, referring to the day after Election Day 2016. “I just think at its heart, that’s what’s caused a lot of this — whether you love Trump or you hate Trump, it is a more partisan time, and it’s infected our committee.”

Democrats peg the start of problems to a slightly different date: March 20, 2017, the day that then-FBI Director James B. Comey told the panel the bureau was running a counterintelligence investigation on Russian interference, and had been looking into potential links between Trump and the Kremlin.

“That was a huge blow to the majority; they then decided they were not going to do public hearings, and the next day, Nunes did his midnight ride,” panel member Rep. Jackie Speier (D-Calif.) said in an interview, referring to a late-night trip Nunes took to the White House on March 21, 2017, to view evidence, he said, indicating the identities of Trump transition team members had been improperly disclosed in intelligence reports. Those allegations would prompt an ethics inquiry.

Nunes, who declined to comment for this report, was cleared of wrongdoing in December.

But by the end of 2017, trust between the parties on the committee had reached a low. Democrats charged Republicans with loading up witnesses to overwhelm the panel and giving those close to Trump a pass not to produce documents, accusing Nunes of blocking their attempts to secure subpoenas for witnesses who refused interviews. Republicans accused Democrats of selectively leaking parts of interviews to the media and grandstanding on television to bias the public’s perception of the probe.

Schiff defended his public presence.

“We have no other tool than exposing what the majority’s doing and often exposing what the majority’s not doing,” he said. “The position they put us in is either go along with an investigation in name only, and be complicit in our silence, or speak out, and that was no choice at all.”

All remaining goodwill was gone by the time the panel’s members began drafting dueling partisan memos about federal law enforcement’s conduct in surveilling a Trump campaign adviser. Democrats, including Schiff, have described a situation in which committee staffers and members had such little communication with their Republican counterparts on Russia that they were forced to discern the majority’s plans from reports appearing on Fox News and in other conservative media.

More recently, according to people familiar with the matter, Democrats say that the panel’s Republicans have been trying to bury them in paperwork by issuing daily updates to the GOP’s 150-page report — but never indicating exactly how or where they’ve amended the document. Republican members say their changes are a part of the editing process.

As tensions have consumed the committee, the stars of its two leaders have risen over dramatically different parts of the electorate. Nunes was recently named a “defender of freedom” by a powerful conservative advocacy group, while Schiff is often referred to as a “liberal hero.” Their public personas could complicate efforts to smooth things over — especially as elsewhere around Washington, the Russia probe is not fading away anytime soon.

“I do not think the committee as currently constituted can heal itself,” Hayden said, expressing a sentiment often murmured on Capitol Hill. House Minority Leader Nancy Pelosi (D-Calif.) has even called for House Speaker Paul D. Ryan (R-Wis.) to remove Nunes as chairman. But neither leader has any plans to replace Nunes or Schiff.

Nunes and Schiff are dissimilar politicians: Before joining the intelligence panel, Nunes was best known as a skilled political operative and fundraiser. Schiff had a reputation as a technocrat and talented prosecutor. But before the Russia probe, both had a healthy working relationship — and panel leaders are confident they can reclaim it.

“Once we move back into the normal oversight work, professionalism will come back through and we’ll go back to work,” Conaway said.

“Even through the worst of our disagreements on Russia, we have compartmentalized the oversight work that we’re doing at the agencies, so all that has continued to go on a very nonpartisan basis,” Schiff said — noting that, unlike some members, he and Nunes still have occasional conversations on the House floor.

But next year, the retirements of several established Republicans could make the panel’s composition more partisan by default. And, ultimately, the committee’s ability to conduct oversight depends on the cooperation of an intelligence community now skeptical of it.

“The art of oversight is neither to be in the pocket of the intelligence community nor to be their implacable opponents,” said Michael Allen, a managing director at Beacon Global Strategies and a former staff director for former committee chairman Mike Rogers. “You’ve got to be tough on them, but they need to know that they can speak freely to you in secure settings about the problems that they face, and to the degree that they feel like they’re walking into a partisan theater, they are going to respond accordingly and be overly cautious.”