Treasury Secretary Steven Mnuchin said allowing Congress to see a whistleblower complaint that allegedly calls into question President Donald Trump’s dealings with Ukraine President Volodymyr Zelensky would set a “terrible precedent.”

But Democrats and some legal experts say granting Congress access to the complaint is required by law.

Mnuchin, during an appearance on CNN’s “State of the Union” Sunday, defended Trump against reports that he repeatedly pressured Zelensky during a July phone call to investigate former Vice President Joe Biden and his son Hunter.

The House Intelligence Committee has opened an investigation into the complaint, including whether Trump withheld military aid from Ukraine as part of his efforts to get Zelensky to investigate Biden, a front-runner in the 2020 Democratic presidential primary.

Michael Atkinson, the inspector general for the U.S. intelligence community, deemed the complaint credible and of “urgent concern,” he wrote in a letter earlier this month to House Intelligence Committee Chairman Adam Schiff (D-Calif.).

But acting Director of National Intelligence Joseph Maguire, whom Trump appointed last month, reportedly said he does not believe the complaint meets the definition of “urgent concern” and has refused to hand it over to Congress.

“There is a whistleblower who wants to bring this information ― his whistleblower complaint ― to Congress, and the White House is preventing that,” CNN’s Jake Tapper told Mnuchin on Sunday. “If there really is nothing there, why shouldn’t the White House just let Congress ... look at this whistleblower complaint?”

Mnuchin responded, “I think that would be a terrible precedent.”

“Conversations between world leaders are meant to be confidential,” he continued. “And if every time someone for political reasons raised a question and all of a sudden those conversations were disclosed publicly ― and when you disclose them to Congress, lots of times they leak into the press ― then why would world leaders want to have conversations together?”

There is no evidence to suggest the U.S intelligence official, who has not been publicly identified, filed the complaint due to political motivations.