A lawyer for billionaire Republican donor Harlan Crow has agreed to speak with staff members of the Senate Judiciary Committee about Crow’s relationship with Supreme Court Justice Clarence Thomas, according to a letter obtained by NBC News.

Michael D. Bopp, Crow’s attorney, said in a letter Monday to Judiciary Committee Chairman Dick Durbin, D-Ill., that while «concerns» persist about lawmakers’ authority to investigate the matter, the panel The Senate plays an «important role in the formulation of legislation.» about our federal court system,» and he «would welcome a discussion with his staff.»

But Durbin and Sen. Sheldon Whitehouse, DR.I., who chairs the subcommittee that oversees the federal courts, criticized Bopp’s latest correspondence in a joint statement Tuesday, calling his letter «a clear and unwarranted refusal to cooperate with the legitimate requests for information from this Committee.»

“Let’s be clear: Harlan Crow doesn’t call the shots here. He is not a branch, or even a member, of the government and he cannot claim the protections and privileges of one,” the two Democrats said. «The Senate Judiciary Committee has clearly established oversight and legislative authority to assess and address the ethical crisis facing the Court. All options are on the table moving forward.»

Earlier in the day, a Judiciary Committee aide told NBC News that Bopp’s latest letter «did not provide a meaningful response» and was not «a bona fide offer.»

“Committee staff have already been in contact with Mr. Crow’s attorney for weeks, and the letter spans six pages blatantly and incorrectly asserting that Congress has no authority to legislate or oversee this space, and one sentence offers to keep in touch. ”said the aide said.

In remarks on the Senate floor Tuesday afternoon, Durbin said that while he would not reject a meeting with Bopp, «all options are on the table to acquire information» the committee is seeking from Crow.

Bopp’s letter comes after he again refused to give Senate Judiciary Democrats information about Thomas’ relationship with Crow, the billionaire businessman. In a May letter to Durbin, Bopp wrote that he believes the committee does not have the authority to «investigate Mr. Crow’s personal friendship with Justice Clarence Thomas» and that Congress «does not have the constitutional power to impose rules and standards of ethics in the Supreme Court.»

That drew a quick rebuke from Durbin and Whitehouse in a letter of May 26.

“His explanation was based on a flawed assessment by the Congressional Article I oversight authority; a restricted reading of the constitutional power of Congress to legislate in matters of governmental ethics; and a totally misplaced view of the separation of powers, a doctrine that is implicated when Congress requests information from coordinated branches of government, not private individuals,” Durbin and Whitehouse wrote. «He also repeatedly conflated personal hospitality with the use of corporate property, highlighting one of the key issues the Committee seeks to address through legislation.»

Bopp’s refusal to comply mirrored what he told the Senate Finance Committee last month, arguing that the panel lacks a legislative purpose in its request for a list of gifts Crow had given Thomas. Sen. Ron Wyden, D-Ore., the committee’s chairman, said in a statement Tuesday that Crow «continues to obstruct basic questions about his gifts to Clarence Thomas and his family.»

Wyden warned that the committee could issue a subpoena, saying, «I have already begun productive discussions with the Finance Committee about next steps to compel responses to our questions from Mr. Crow, including by subpoena, and those discussions will continue.»

Thomas has come under scrutiny over allegations reported by ProPublica that he failed to properly disclose trips and gifts paid for by Crow, the sale of the estates of Thomas and his relatives to Crow and the tuition that Crow paid for one of the judge’s relatives.

Thomas said after the ProPublica reports that he had been told the trips and gifts were «personal hospitality from close personal friends» and that he was under the impression they did not have to be disclosed in the disclosures.

Durbin and other Democrats on the Judiciary Committee asked Crow to provide an itemized list of gifts worth more than $415 that he gave to Thomas or any other judge or their relatives. They also asked Crow to provide a complete list of real estate transactions, transportation, lodging, and admission to private clubs that he could have provided.

The Supreme Court and Thomas did not immediately respond to NBC News’ request for comment.

kate santaliz and frank thorp contributed.