Washington — The head of the Senate Finance Committee said Tuesday that the panel is discussing "next steps" to force GOP megadonor Harlan Crow to provide information about his ties to Supreme Court Justice Clarence Thomas, including through a subpoena, after Crow again rebuffed requests for an accounting of the gifts and accommodations he provided to the justice.

Democratic Sen. Ron Wyden of Oregon, the committee's chairman, accused Crow in a statement of "doubling down on bogus legal theories." Last week, the Texas real estate developer refused a second request to provide the Finance panel with detailed information about the flights, gifts and trips aboard Crow's yacht that Thomas received over the course of their 25-year friendship.

Wyden asked Crow for the accounting of his arrangements with Thomas for the first time in late April and again in mid-May. The Oregon Democrat also requested information about three properties in Georgia that Crow bought from Thomas and his relatives, as well as a list of additional gifts or payments worth more than $1,000.

"Far too often, efforts to investigate real life tax practices of the ultra-wealthy and powerful end with this kind of vague, carefully-worded assurance that everything is on the level," the senator said of the responses from Crow's lawyer, Michael Bopp. "That's simply not good enough. This is exactly why the Finance Committee is pursuing this matter as part of its broader review of gift and estate tax practices of ultra-high net worth individuals. I've already begun productive discussions with the Finance Committee on next steps to compel answers to our questions from Mr. Crow, including by subpoena, and those discussions will continue."

Wyden again accused Crow of attempting to "stonewall basic questions about his gifts to Clarence Thomas and his family."

"If anything, the most recent letter from his attorney raises more questions than it answers," he said.

In the letter to Wyden, dated June 2, Bopp asserted that the senator "fails to establish a valid justification" for what he called "the committee's impermissible legislative tax audit" of Crow, and does not identify "any legitimate legislative need" for requesting the information.

Legislative efforts addressing issues surrounding estate and gift taxes are not active in the current Congress, Bopp argued.

"A desire to focus on Justice Thomas, not the intricacies of the gift tax, appears to have been the genesis of this committee inquiry," he wrote.

Wyden, though, has said the information from Crow is needed for the committee to better understand any federal tax considerations arising from his gifts to Thomas, and noted the panel has extensively examined matters related to the gift tax.

Bopp also argued the May 17 response from the chairman did not address separation of powers concerns raised by the committee's request for financial personal information relating to Crow's friendship with a sitting member of the Supreme Court.

"The Committee has no authority to target specific individuals' personal financial information when the asserted legislative goals could be served in less intrusive ways," he continued.

In addition to the Finance Committee, Democrats on the Judiciary Committee have separately demanded Crow turn over detailed information about his financial arrangements, travel and gifts to Thomas, though he has spurned their requests, too.

Congressional scrutiny of their relationship began in response to a series of reports from the news outlet ProPublica that detailed Thomas and Crow's relationship. Among the revelations was that Crow paid for two years of tuition at private schools for Thomas' grandnephew, which the justice did not disclose on financial disclosure forms. 

Chief Justice John Roberts was invited to testify before the Judiciary Committee, but declined. Instead, he sent a letter that included a three-page "Statement on Ethics Principles and Practices" signed by the nine justices.

The statement did little to assuage Democrats' concerns about the Supreme Court and its ethics standards, and they have warned that they could take legislative action to strengthen the ethical rules that govern the justices.