WASHINGTON — The House Jan. 6 select committee’s pursuit of what led to the attack on the Capitol is shaping up to be a fight over congressional oversight authority that may have lasting effects on the way the legislative branch conducts investigations.

The panel in August asked 35 telecommunications, email and social media companies, such as Apple and Verizon, to preserve records — from April 1, 2020, through Jan. 31, 2021 — relating to certain people who could be of interest to the inquiry. Those ranged from persons criminally charged by the Department of Justice in connection with the riot to rally organizers, and to people potentially involved in discussions to challenge the certification of the 2020 presidential results, which could extend to lawmakers.

“Any information that’s going to be important to the committee’s work, we’re going to seek it,” Chairman Bennie Thompson, D-Miss., said last week when asked if his panel was seeking text messages and other communications of lawmakers.

House Republican leader Kevin McCarthy and Rep. Jim Jordan, R-Ohio, are two members who are publicly known to have spoken with President Donald Trump on the day of the riot. Shortly after the preservation orders went out, McCarthy warned that a future Republican House majority “will not forget” if companies turned over private data to the select committee.

Rep. Adam B. Schiff, who serves on the Jan. 6 panel, said members with information of interest won’t be excluded from scrutiny.

“Our committee is of the mind that no one gets a pass,” the California Democrat said Wednesday. “If there were members involved in the events leading up to Jan. 6 or on Jan. 6 or have relevant information about conversations with the president or others in the White House, then those are not off limits.”

Asked what would happen if a lawmaker doesn’t agree to talk with the committee, Schiff said, “We’ll cross that bridge when we come to it.”

On Sept. 23, the panel issued subpoenas to four people close to Trump leading up to or on the date of the insurrection: Mark Meadows, the White House chief of staff; Dan Scavino, the White House deputy chief of staff for communications; Kashyap Patel, a Pentagon official; and Stephen Bannon, a former Trump adviser.

Patel and Bannon have been instructed to sit for depositions on Oct. 14. Meadows and Scavino are scheduled for the following day. All have been mandated to produce certain documents by Oct. 7.

But it’s not yet clear how the panel will approach members of Congress who are of interest to the investigation.

Thompson said last week that subpoenas have not been sent out to individual lawmakers but noted that “it could happen.”

On Tuesday, he said the panel plans “to issue some additional subpoenas before the week’s out.” Asked if the subpoenas would be limited to the executive branch or go beyond it, Thompson replied, “Actually, it could be both.”

This next round is slated to be a larger one.

“It could be 10, 12,” Thompson said of the number of subpoenas that would be issued this week, which “could be before Friday.”

The resolution that established the select committee empowers it with a wide scope of authority to investigate the facts, circumstances and causes related to the Jan. 6 insurrection at the Capitol. That expansive charge will lead the panel to produce a final report to the House, with findings and recommendations for corrective measures. This could include legislative proposals geared toward preventing future acts of domestic terrorism; improving the security posture of the Capitol complex; and strengthening the security and resilience of the United States against violent domestic extremism.

Republicans say the panel’s potential interest in obtaining phone records of hundreds of people, including lawmakers and those who planned the rally, would be a vast overreach of congressional oversight authority — with some exceptions.

Courts have held that a congressional subpoena must serve a “valid legislative purpose” and that Congress cannot issue a subpoena for “law enforcement” because that power is left to the judicial and executive branches. Further, courts have said that recipients of congressional subpoenas retain their constitutional rights and privileges throughout an investigation.

There could be a valid legislative purpose for phone records and other communications of some individuals in relation to Jan. 6, such as members of the Capitol Police Board, according to a source familiar with House Republican leaders’ thinking.

The source said those serving on the Capitol Police Board at the time — the House sergeant-at-arms, Senate sergeant-at-arms, architect of the Capitol and Capitol Police chief (a nonvoting member) — could be subject to a subpoena because they operated under a statute written by Congress and were responsible for security planning and decisions up to and including that day.

It would be a valid legislative purpose, according to the source, because Congress needs to know what happened regarding the security planning and whether the Capitol Police Board law worked the way it was intended to work — and if it didn’t, the information would be integral to Congress’ ability to fix the law.

“The phone records of an individual member, or attendee of the rally or permit applicant … you would have a very hard time convincing a court of law that there is a valid legislative purpose to be rifling through an individual’s phone records absent that,” the source said.

Former Rep. Tom Davis, a onetime chairman of the Oversight Committee, said going after members’ phone records would set a dangerous precedent and harm the institution.

“We’re breaking some brand new ground on this kind of thing, and once you cross this Rubicon, there’s no going back,” the Virginia Republican said, adding that it was a “slippery slope.”

Davis noted that while he could make a case for a legislative purpose behind seeking such records, it would have grave unintended consequences in the long term.

“I don’t think this would be a one-off, that this is the only time they’ll do it,” he said. “I think you’ll set a precedent here. You’ll rue the day you started this because the next group comes in and finds a justification, etc. It would be ruinous to the institution. If they can find it in a different way, that’s all well and good.”

Jordan said in an interview Thursday that he had not heard anything regarding his phone records from the select committee or from his phone provider. While he said he has “nothing to hide,” he alluded to Republicans seeking retribution the next time they are in the majority.

“If they’re going to go down this unprecedented road, then I know a lot of constituents of mine and folks around the country who would love to hear from Mr. Swalwell about his supposed ties with a Chinese communist spy and lots of constituents who’d love to hear from Mr. Schiff about his office’s contact with the so-called anonymous whistleblower,” Jordan said, referring to Rep. Eric Swalwell, D-Calif., and Schiff, both of whom served as impeachment managers and butted heads with Jordan during the impeachments of Trump.

But the select panel is pressing forward to get the information they want.

“We’re going to get it any way we can,” Thompson said regarding records sought by the panel.

Illinois Rep. Adam Kinzinger, one of two Republicans on the select committee, said panelists met Tuesday and are in the process of gathering information and “people are coming in for interviews.”

The panel is going through mounds of information and conducting interviews with people who are cooperating, and it may be some time before the next public hearing. The first and most recent public hearing was in July.

“We just got so much information we’re trying to go through,” Thompson said Tuesday. “Actually, we’re getting a lot of stuff that we didn’t know about, so there might not be a need for an immediate hearing just given the cooperation we’re getting from witnesses and other things.”