A new subcommittee being set up by the House’s new GOP majority to investigate what it calls the “weaponization” of the federal government will have virtually unprecedented power following some last-minute additions to the text of a resolution teed up for a vote next week.

Establishment of the committee was one of several concessions made by the House’s new speaker, Kevin McCarthy, as he wrangled the votes he needed to win his post last week. Hardline Republicans have deemed the new subcommittee a new “Church Committee,” a reference to an investigation into civil liberties violations by the executive branch in the 1970s by an Idaho senator, Frank Church.

The new subcommittee is expected to take on investigations into law enforcement excesses in the inquiry into the events of January 6, which is ongoing, and cooperation between a range of federal agencies — including spy agencies — and social media companies during the Covid pandemic, among other issues.

Following some last-minute additions to the language of the resolution creating the subcommittee, the panel will be allowed to investigate “ongoing criminal investigations” and have access to highly classified intelligence that currently is only provided to the House Intelligence Committee.

Earlier versions of the resolution, according to a report in Politico, made no mention of the intelligence committee, and limited the subcommittee’s scope to investigations of only the FBI, and the departments of Homeland Security and Justice.

“We will hold the swamp accountable, from the withdrawal of Afghanistan, to the origins of Covid and to the weaponization of the F.B.I.,” Mr. McCarthy shortly after being sworn in as secretary early Saturday morning. “Let me be very clear: We will use the power of the purse and the power of the subpoena to get the job done.”

The addition of the “ongoing criminal investigations” put the panel on a collision course with President Biden’s justice department and the new special counsel, Jack Smith, tasked with investigating President Trump’s efforts to overturn the 2020 election and his hoarding of classified documents at his Mar-a-Lago estate. Attorney General Garland said last week the department’s investigation in both those cases, as well as the 2021 riot at the Capitol, are “far from over.”

In the past, the Justice Department has refused to turn over evidence from ongoing investigations to Congress, a custom that would most likely be continued by Mr. Garland even in the face of subpoenas from the new subcommittee.

The subcommittee will be part of the House’s Judiciary committee, which is expected to be led by Ohio’s Jim Jordan, a staunch ally of Mr. Trump. In an appearance on Fox News Sunday, Mr. Jordan said Congress needs to get to the bottom of the government suppression of free speech as detailed in recent reporting in the “Twitter Files” and the FBI’s efforts to quash reporting about President Biden’s son, Hunter, before the 2020 election.

“We have a duty to get into these agencies and look at how they have been weaponized to go against the very people they are supposed to represent, how they have infringed on First Amendment liberties of the American people,” Mr. Jordan said. “And we’re going to do that. We’re going to do it in a way that’s consistent with the Constitution, but we’re going to do it vigorously, we’re going to do it aggressively, because that’s our job.”

While the makeup of the subcommittee has yet to be decided, some members of Congress eligible for roles on the body insist that they will sit on it regardless of whether they are part of the investigations being investigated by the committee. A Pennsylvania Republican, Scott Perry, whose phone was seized by federal investigators in the January 6 probe, bristled at the prospect of being excluded because of his potential involvement in the riot. 

“Why should I be limited?” Mr. Perry said Sunday on ABC’s “This Week.” “Why should anybody be limited just because someone has made an accusation? Everybody in America is innocent until proven otherwise.”