A congressional watchdog office is looking into whether President Donald Trump improperly upheld a nine-figure aid package to Ukraine, despite Congress having already approved the money.

The Government Accountability Office is investigating the White House’s hold on the aid, a spokesperson confirmed to The Wall Street Journal on Thursday.

The nearly $400 million package has played a central role in the House impeachment inquiry of Trump’s actions — the EU ambassador acknowledged this week that he told the Ukrainians that the money was dependent on announcing investigations that would be helpful to Trump.

But the GAO inquiry actually came in response to a request from the other side of the Capitol Building, specifically, to a question from Sen. Chris Van Hollen (D-MD) to the investigative office during a hearing.

To coerce Ukraine to interfere in our elections on his behalf, Trump withheld critical aid. Trump knew what he was doing was illegal, so he failed to notify Congress in violation of the Impoundment Control Act. More from my exchange with the @GAO: pic.twitter.com/Ejeg1pSLwA — Chris Van Hollen (@ChrisVanHollen) October 30, 2019

In the exchange, Van Hollen asked U.S. Comptroller General Gene Dadaro, who leads GAO, whether it would be illegal for the executive branch to “run out the clock” on appropriated money as a backdoor method for not spending funds that Congress allocated.

The GAO would be responsible for enforcing spending issues like this, and the agency released an opinion on the law in question, the Impoundment Control Act, last year.

“What this opinion says is if you try to withhold the money and not give Congress the 45 days [to approve such a recission] and the money expires toward the end of the year, that’s not a proper recission,” Dadaro testified. “That’s not contemplated under the law to operate that way.”

“The Ukraine money was not released within those 45 days,” Van Hollen said. “Maybe you can get back to me on whether GAO told the administration they were in dangerous territory.”

That the administration was withholding the congressionally allocated aid to Ukraine was only revealed months after that allocation — in a Politico article in late August. Within two weeks and under mounting public pressure, the White House released the funds.

Pointing to articles from LawFare and Just Security on the holdup, Van Hollen raised the prospect that even though the White House ended up releasing the funds, the failure to notify Congress would itself have been a violation of the law.

“If you can just get back to me on whether you agree, and number two, what’s our recourse at the end of the day, as a Congress, if they don’t do it?” he asked.

The White House told the Journal that it “fully complied with the law.”

“Congress is notified if the Administration intends to rescind, defer, reprogram, or transfer funding, but in this case none of those things occurred and the funding was obligated as planned,” said Rachel Semmel, a spokesperson for the White House budget office.