Senate Finance ranking member Ron Wyden threatened to hold up Treasury Department nominees after receiving an “unresponsive and wholly unacceptable” response to questions he posed about the department’s refusal to release President Donald Trump’s tax returns.

“If the Treasury Department refuses to answer our questions, I am prepared to again place a hold on department nominees as I did previously when routine requests for information went unanswered,” the Oregon Democrat said in a statement Thursday.

[Treasury won’t meet deadline to release Trump tax returns]

Five Treasury Department nominees currently await Senate confirmation: Treasury General Counsel Brent McIntosh as undersecretary for international affairs, Michael Faulkender as an assistant secretary, Brian McGuire and Geoffrey William Seiji Okamoto as deputy undersecretaries, and Brian Callanan as general counsel.

Streamlining of the confirmation process, along with changing the rules to require a simple majority vote to confirm nominees, has lessened the impact of a senatorial hold.

Wyden, though, has additional options, and he has already made it clear that McIntosh will face detailed questioning during his confirmation hearing, regarding his role as Treasury general counsel in Secretary Steven Mnuchin’s May 6 decision to not hand over Trump’s tax returns.

Two weeks ago, Wyden wrote a letter asking for details behind Mnuchin’s decision to not supply six years of the president’s personal tax returns and six years of tax returns from eight Trump businesses.

[Ways and Means chairman asks for Trump’s tax returns]

House Ways and Means Chairman Richard E. Neal had requested the returns April 3, citing Section 6103 of the tax code, which states that upon “written request” from the chairman of either the House Ways and Means or Senate Finance committees, “the [Treasury] Secretary shall furnish such committee with any return or return information specified.”

Mnuchin turned down the written request, arguing that Neal’s request lacked a “legitimate legislative purpose.” The Massachusetts Democrat followed that with a subpoena and a May 16 deadline. Mnuchin did not comply with the subpoena. Neal has indicated his next step will be to take the case to federal court.

In a May 14 letter, Wyden asked Mnuchin for a count of how many times congressional committees had requested tax returns from Treasury and the IRS since 2000, how many times the requests were filled, and whether an opinion on congressional authority to request tax returns had ever been sought from the Justice Department as Mnuchin did in this instance.

It was a May 28 response to that letter from Treasury’s Office of Legislative Affairs that Wyden blasted for not being responsive to his questions.

[Trump: ‘I Don’t Care’ if House Democrats Release My Tax Returns]

In that letter, Justin W. Sok, a senior adviser to the Treasury’s Office of Legislative Affairs, wrote that Neal’s request could not be “meaningfully compared” to any previous requests under Section 6103, since it targeted a single taxpayer’s documents “for the purpose of releasing those returns to the public.”

In a statement last week, Wyden noted that McIntosh was “integral” to Mnuchin’s decision “to break the law and refuse to comply” with the request for Trump’s tax returns.

Wyden added that if “McIntosh wants a promotion, he needs to be prepared to thoroughly answer senators’ questions about his role.”