(CNN) - The top Democrat on the Senate Finance Committee is moving ahead with a threat to hold up any Treasury Department nominees over resistance from two agencies overseeing the release of President Donald Trump's personal tax returns.
"The administration's blanket obstruction of all oversight as it relates to Donald Trump's tax returns cannot go unanswered -- Congress needs to take action to force the administration to comply oversight," Oregon Sen. Ron Wyden said in a statement on Wednesday.
Trump has broken with decades of presidential precedent by refusing to make his personal tax information public, and has retained his interest in the Trump Organization while in office.
In late May, Wyden threatened to place a hold on nominees appointed by Trump, if Treasury Secretary Steven Mnuchin and Internal Revenue Service Commissioner Charles Rettig failed to adequately answer congressional requests.
Wyden said he has received "non-answers or no responses at all" from both of the agencies on questions about when political appointees learned of a memo prepared in anticipation of congressional request for Trump's tax returns among other queries. The IRS has yet to respond to the senator's request, which carried a June 11 deadline.
"Congress has a constitutional obligation to conduct oversight of the executive branch so I am placing a hold on Treasury Department nominees," Wyden said.
He also urged the committee, which is led by Republican Sen. Charles Grassley of Iowa, not to proceed with a hearing for Brent McIntosh, the current general counsel, who has been nominated to be Treasury undersecretary for international affairs.
"Mr. McIntosh was central to the Treasury Department's decision making and without additional context on the process, committee members will not be able to ask informed questions," Wyden said.
Mnuchin has refused to comply with a subpoena from House Democrats for six years of Trump's tax returns, citing Department of Justice legal advice. House Ways and Means Chairman Richard Neal has requested the documents under an obscure statute that grants the heads of tax-writing committees access to tax returns for oversight purposes.
Trump has several nominees to the Treasury Department currently waiting for Senate confirmation, including Brian McGuire, nominee for assistant secretary for legislative affairs; Michael Faulkender, the nominee for assistant secretary of economic policy; Brian Callanan, the nominee for general counsel and Geoffrey William Seiji Okamoto, nominated for deputy undersecretary.
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