Former President Donald Trump on Monday sought to block the release of documents related to the Jan. 6 Capitol insurrection to a congressional committee investigating the attack, challenging President Joe Biden’s initial decision to waive executive privilege.

In a federal lawsuit, Trump said the committee’s request was “almost limitless in scope,” and sought records with no reasonable connection to that day. He called it a “vexatious, illegal fishing expedition” that was “untethered from any legitimate legislative purpose,” according to the papers filed in federal court in the District of Columbia.

Trump’s lawsuit was expected, as he had said he would challenge the investigation and at least one ally, Steve Bannon, has defied a subpoena. But the legal challenge went beyond the initial 125 pages of records that Biden recently cleared for release to the committee. The suit, which names the committee as well as the National Archives, seeks to invalidate the entirety of the congressional request, calling it overly broad, unduly burdensome and a challenge to separation of powers. It requests a court injunction to bar the archivist from producing the documents.

The Biden administration, in clearing the documents for release, said the violent siege of the Capitol was such an extraordinary circumstance that it merited waiving the privilege that usually protects White House communications.

In a letter obtained by The Associated Press, the White House worked to undercut Bannon’s argument before a scheduled committee vote on whether to recommend criminal contempt charges against him. Bannon is a onetime White House adviser who left the administration years before the insurrection.

Deputy Counsel Jonathan Su wrote that the president’s decision on the documents applied to Bannon, too, and “at this point we are not aware of any basis for your client’s refusal to appear for a deposition.”

“President Biden’s determination that an assertion of privilege is not justified with respect to these subjects applies to your client’s deposition testimony and to any documents your client may possess concerning either subject,” Su wrote to Bannon’s lawyer.

Bannon’s attorney said he had not yet seen the letter and could not comment on it. While Bannon has said he needs a court order before complying with his subpoena, former White House Chief of Staff Mark Meadows and former White House and Pentagon aide Kashyap Patel are negotiating with the committee. It is unclear whether a fourth former White House aide, Dan Scavino, will comply.

The committee has also subpoenaed more than a dozen people who helped plan Trump rallies ahead of the siege, and some of them have already said they would turn over documents and give testimony.

Lawmakers want the documents as part of their investigation into how a mob of Trump supporters stormed the Capitol building on Jan. 6 in a violent effort to halt the certification of Biden’s election win. The committee demanded a broad range of executive branch papers related to intelligence gathered before the attack, security preparations during and before the siege, the pro-Trump rallies held that day and Trump’s false claims that he won the election, among other matters.

Trump’s lawsuit says the “boundless requests included over fifty individual requests for documents and information, and mentioned more than thirty individuals, including those working inside and outside government.”

The files must be withheld, the lawsuit says, because they could include “conversations with (or about) foreign leaders, attorney work product, the most sensitive of national security secrets, along with any and all privileged communications among a pool of potentially hundreds of people.”

The suit also challenges the legality of the Presidential Records Act, arguing that allowing an incumbent president to waive executive privilege of a predecessor just months after they left office is inherently unconstitutional. Biden has said he would go through each request separately to determine whether that privilege should be waived.

While not spelled out in the Constitution, executive privilege has developed to protect a president’s ability to obtain candid counsel from his advisers without fear of immediate public disclosure and to protect his confidential communications relating to official responsibilities.

But that privilege has its limitations in extraordinary situations, as exemplified during the Watergate scandal, when the Supreme Court ruled it could not be used to shield the release of secret Oval Office tapes sought in a criminal inquiry, and following the Sept. 11 terrorist attacks.

Monday’s lawsuit was filed by Jesse Binnall, an attorney based in Alexandria, Virginia, who represented Trump in an unsuccessful lawsuit late last year seeking to overturn Biden’s victory in Nevada. Trump and his allies have continued to make baseless claims about voter fraud in the 2020 election.

Trump’s suit quotes from the U.S. Supreme Court’s 2020 ruling in a case by House committees seeking the then-sitting president’s tax returns and other financial records. But that case involved courts enforcing a congressional subpoena. The high court in that case directed lower courts t o apply a balancing test to determine whether to turn over the records — it’s still pending.

Neither the White House nor the select committee had an immediate comment.