The Senate impeachment trial of President Donald Trump formally began Tuesday, kicking off with debate over the rules of how the trial would work as outlined in a resolution from Senate majority leader Mitch McConnell.

Among the many questions that this entire impeachment process has raised, a critical one has emerged repeatedly.

Does a president's conduct need to rise to the level of a crime for him to be convicted in the Senate?

For weeks, Republicans have argued that the articles of impeachment passed by the House back in December do not rise to that level of a statutory crime.

Meanwhile, Democrats contend that the president does not have to commit a crime but a constitutional violation in order to be impeached.

So when a particular piece of news broke last week that highlighted this tension, we wanted to take a deeper look.

Thursday, the government accountability office, which is a nonpartisan agency that reports to Congress, ruled that the White House's office of management and budget, the OMB, violated federal law when it withheld security aimed Ukraine last year.

So how much does this ruling matter to the outcome of the Senate trial? What legal weight does a decision from the GAO actually carry?

And will this ruling be considered as House Democrats and the Trump team make their cases to the Senate?

This is Ken Hedizet, a podcast that explores the powers and limitations of the American presidency and what happens when branches of government collide.

I'm Allison Michaels.

To find out more about the government accountability offices role in Washington, I turn to the post's economic policy reporter, Jeff Stein, who reported on the GAO's decision last week.

I ask him to start by explaining what the GAO is, exactly.

The GAO is Congress's nonpartisan watchdog agency and basically their job is to investigate and police and figure out if the federal government is spending money that's been allocated by Congress appropriately.

Obviously we have a separation of powers in which Congress has invested in it, the power of the purse, the power to decide where money goes.

It's the executive branch, which Trump is obviously the home of at the sides. How that gets executed in a portion.

And so there's been obviously decades, centuries, really, of a tug of war in which Congress has implemented certain laws to govern this process and sculpt it and shape where the executive branch can and cannot have discretion over how money is spent.

And GAO is really at the center of ensuring that the executive branch does fulfill under the law what Congress told it to do.

So to be clear, it's a nonpartisan agency.

Yes. If you ask people in the White House, they'll tell you, and I think with a degree of fairness, that the GAO reports to Congress and in some ways, according to them, reflects the preferences of Congress.

Because that's what they would say. Congress says that just because they report to them doesn't mean that they're prejudiced in any way to the legislative branch.

But in terms of between the Democrats and their Republicans, yes, it's nonpartisan and widely respected by members of both parties.

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