The facts, with their well-known liberal bias, are going to make it much harder for Senate Republicans to willfully conduct a sham impeachment hearing. The latest development that they cannot ignore is the determination by the Government Accountability Office that Trump's budget office broke the law in withholding aid to Ukraine.
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The GAO, a nonpartisan congressional office like the Congressional Budget Office, reviewed the Office of Management and Budget's (OMB) actions in withholding security assistance to Ukraine and its rationale for doing so. "Faithful execution of the law," GAO says in the memo, "does not permit the President to substitute his own policy priorities for those that Congress has enacted into law. OMB withheld funds for a policy reason, which is not permitted under the Impoundment Control Act (ICA). […] Therefore, we conclude that OMB violated the ICA. [emphasis added]" The ICA was enacted in 1974, "in response to President Nixon's executive overreach." It allows for the executive to delay or cancel funding, but to do so "he or she must first secure a law providing Congressional approval to rescind the funding in question" and he or she has to have valid, programmatic reasons for doing so.
Sen. Chris Van Hollen tweeted a copy of the decision, saying "This bombshell legal opinion from the independent @USGAO demonstrates, without a doubt, that the Trump Administration illegally withheld assistance from Ukraine and the public evidence shows that the president himself ordered this illegal act."
Trump ordered the funds withheld. There's no question of that, and he's admitted it publicly. Acting chief of staff Mick Mulvaney admitted it, and confessed that it was a quid pro quo for dirt on Joe and Hunter Biden. That's blatantly illegal. The GAO says so.