'What were they hiding?': Trump critics insist 'explosive' White House email shows exactly why key witnesses must testify in Senate trial

Internal White House emails obtained late Friday night by the Center for Public Integrity showed that a budget official ordered the Pentagon to put a hold on congressionally appropriated military aid to Ukraine—and to keep quiet about the freeze—just 90 minutes after President Donald Trump's infamous July 25 phone call with Ukrainian leader Volodymyr Zelensky.

"Given the sensitive nature of the request, I appreciate your keeping that information closely held to those who need to know to execute the direction," Michael Duffey, a Trump-appointed senior official with the Office of Management and Budget (OMB), wrote in a July 25 email to Pentagon Comptroller Elaine McCusker and other Trump administration officials.

The email was just one revelation in the 146 pages of heavily redacted documents obtained by the Center for Public Integrity (CPI) after it won a Freedom of Information Act lawsuit against the Trump administration.

As CPI national security editor R. Jeffrey Smith wrote Friday, U.S. law mandates that "once Congress appropriates funds—like the Ukraine assistance—and the president signs the relevant spending bill, the executive branch must spend those funds."

"A president cannot simply ignore Congress' direction, no matter how inconvenient or unappealing that instruction might be," Smith noted. "If funds are withheld or shifted elsewhere, this cannot be done in secret, and Congress must approve."

Senate Minority Leader Chuck Schumer (D-N.Y.) quickly seized upon the email as further evidence that Duffey, Acting White House Chief of Staff Mick Mulvaney, and other witnesses must testify in Trump's impeachment trial in the Senate.

"What were they hiding?" Schumer, holding a copy of Duffey's email to the Pentagon, asked during a press conference on Sunday. "This email is explosive. A top administration official, one that we've requested, is saying 'stop the aid' 91 minutes after Trump called Zelensky, and said 'keep it hush-hush.' What more do you need to request a witness?"

"If there's nothing wrong with withholding the aid, why didn't Mr. Duffey want anyone to know about what he was doing?" Schumer added. "If this is a perfect conversation, if this is [an] OK action, why are they trying to hush it up?"

Duffey's email was made public just days after the House of Representatives approved two articles of impeachment against Trump, paving the way for a trial in the Republican-controlled Senate.

In a column on Monday, the Washington Post's Paul Waldman argued that the email "directly undermines the justification Trump's defenders have so often offered for holding up the aid: that it was not to coerce Ukraine into helping Trump's reelection campaign but was merely a product of Trump's passionate commitment to fighting corruption (please stop laughing)."

"If that were true, the White House would have wanted to make sure that every relevant official in the government was informed about the suspension of aid and why it was being undertaken," Waldman wrote. "The White House might even have wanted to talk about it publicly. Instead, the White House treated the suspension of aid as a secret so dangerous that if if were discovered it would be a disaster."

"And they were right," added Waldman. "When it finally did become public, the result was the impeachment of the president."