The Democratic-led Judiciary Committee held a hearing on the subject in May.
Crow, a major Republican donor, last month, rejected the panel's request for a meeting.
Separately, Bopp declined to provide another Democratic-led Senate panel, the Finance Committee, any personal financial information about Crow, it said.
In a statement, the panel accused Crow of "stonewalling" and "doubling down on bogus legal theories."
The news outlet ProPublica has detailed the ties between Thomas and Crow.
Persons:
Harlan Crow's, Clarence Thomas, Thomas, Crow, Crow's, Michael Bopp, Dick Durbin, Sheldon Whitehouse, Bopp, Ron Wyden, Neil Gorsuch, Susan Heavey, Kanishka Singh, Will Dunham
Organizations:
U.S, Supreme, Republican, Democratic, Finance Committee, Finance, Politico, Thomson
Locations:
Texas, Colorado