As President Trump's impeachment trial moves into opening arguments Wednesday, Democratic prosecutors are expected to highlight a newly released government watchdog report finding the administration broke the law by freezing millions in military aid to Ukraine.

But the same nonpartisan agency, the Government Accountability Office, has accused numerous past presidents and administrations of breaking the law—without impeachment being discussed.

GAO SAYS TRUMP ADMINISTRATION BROKE LAW BY WITHHOLDING UKRAINE AID

In this case, while the alleged violation had triggered impeachment proceedings well before the GAO report a week ago, the report was still used by Democrats to bolster their case heading into the Senate trial. Republicans, though, are poised to argue that the violations in the GAO report hardly rise to the level of impeachment -- and have repeatedly pointed out that GAO findings in the past have not merited much national attention.

Over the weekend, Sen. John Cornyn, R-Texas, criticized the findings and said the violations do not meet the standards for trying to remove Trump from office.

"[It's] certainly not a crime and something that no one had ever dreamed in the past would have risen to the level of impeachment," Cornyn said on CBS News' "Face the Nation." "This is the first time in history where a president has been impeached for a non-crime, for events that never occurred, ultimately the investigation never took place and ultimately the aid was delivered."

In 2016, the GAO determined that the Obama administration broke its own health care law. The GAO said the administration broke the Affordable Care Act due to its handling of “transitional reinsurance.” The program was slated to collect fees from employers and other private health insurance plans, with $5 billion of that fee going directly to the Treasury Department. When the fee fell short, according to the GAO, the Department of Health and Human Services failed to allocate that share of money to the Treasury.

In a separate report released in 2015, the GAO determined the Obama administration broke the law—again—this time, with regard to the Environmental Protection Agency. The GAO claimed the EPA violated federal law by engaging in “covert propaganda” when it used social media to urge support for an Obama administration rule to protect the nation’s waters.

And in 2014, the GAO ruled that the Obama administration broke the law when the Pentagon swapped Army Sgt. Bowe Bergdahl for five Taliban leaders, and used $988,400 from a wartime account to make the transfer.

With regard to budgetary issues, the GAO was critical of former Presidents George W. Bush, Bill Clinton and the late President George H.W. Bush regarding impoundments—acts by presidents of not spending money that has been appropriated by Congress.

Fast forward to 2020, and the Democratic impeachment managers reportedly plan to highlight the results of the latest GAO review in their effort to remove the president from office.

“This is a big part of our case,” a Democratic leadership aide told Axios on Tuesday. “It shows the extent to the president went to advance his scheme; he went so far to break the law. It's an important piece of evidence and only adds to the mountain and body of evidence that we already have."

The GAO report found that the Office of Management and Budget broke the law in holding up the aid, which Congress passed less than a year ago, saying “the president is not vested with the power to ignore or amend any such duly enacted law."

CORNYN RIPS GAO REPORT THAT FOUND WHITE HOUSE VIOLATED LAW IN FREEZING UKRAINE AID

The aid in question was held up last summer on orders from Trump, but was released in September after Congress pushed for its release and a whistleblower's complaint about Trump's July call with the Ukrainian leader became public. This came as Trump was pressing Kiev for investigations into Democrats, leading critics to allege a quid pro quo.

The independent agency, which reports to Congress, said OMB violated the Impoundment Control Act by delaying the security assistance for “policy reasons,” rather than technical budgetary needs.

“Faithful execution of the law does not permit the president to substitute his own policy priorities for those that Congress has enacted into law,” wrote the agency's general counsel, Thomas Armstrong, in the report.

OMB has argued the hold was appropriate and necessary.

“We disagree with GAO's opinion. OMB uses its apportionment authority to ensure taxpayer dollars are properly spent consistent with the president's priorities and with the law," said OMB spokeswoman Rachel Semmel.

Fox News' Andrew O'Reilly, Tyler Olson and The Associated Press contributed to this report.