The evidence of President’s Trump’s wrongdoing is piling ever higher. It now includes his own phone call with the Ukrainian president; texts, emails and other documents; and the testimony of multiple officials, all telling essentially the same story: that Trump and his lawyer Rudy Giuliani tried to strong-arm Ukraine into helping his reelection campaign.

Faced with all that, Republicans are now saying this: Nothing is more important than revealing the identity of the whistleblower whose complaint touched off this scandal. Without knowing who that person is, we can’t judge Trump.

So Sen. Rand Paul (R-Ky.) angrily demands that the media print the whistleblower’s name. “Nobody should be prosecuted based on an anonymous accusation,” says Sen. Lindsey O. Graham (R-S.C.). “Without the whistleblower complaint none of this would be going on, so I want to know who the person is.”

“I can’t control what goes on in the House, but if it comes over to the Senate and we have a trial I’m going to want to know who the whistleblower is,” says Sen. Josh Hawley (R-Mo.). “How else are we going to evaluate the content and the truthfulness of these people if we don’t know who they are?”

This idea is being hammered home multiple times a day across conservative media. So it’s important that we understand two things about this argument. First, it’s deeply, profoundly, absurdly wrong. And second, it’s being offered for no reason other than to pull attention away from the substance of Trump’s misdeeds.

While it might be of some historical interest, at this point the whistleblower’s identity is irrelevant. No one is asking that we take their word on anything. They sounded the alarm that touched off an investigation, but the evidence that will provide the grounds for impeachment is coming from Trump’s own words and the testimony of multiple officials in his administration, not the whistleblower.

The whistleblower was the equivalent of someone who made an anonymous call to the police saying that there’s a robbery going on at the First National Bank. Once the police get there and catch a bunch of guys wearing masks and holding sacks of money, it doesn’t matter who made the call or what their motives were. Maybe it was a passerby, or maybe it was the estranged wife of the leader of the gang. It doesn’t change the fact that the bank was robbed and we know who the robbers are.

Furthermore, just about everything the whistleblower alleged has been corroborated. The whistleblower accurately described the call between Trump and Ukraine President Volodymyr Zelensky, the efforts to keep the call transcript concealed, the fact that military aid to Ukraine was upheld at the president’s direction, the involvement of Giuliani in pressuring the Ukrainian government and the discomfort of American diplomats, among other things.

All this has been confirmed by Trump’s words and the testimony of administration officials and career civil servants. We don’t need to know the whistleblower’s identity to assess their credibility, because we aren’t relying on their credibility.

Yet unless I’m missing something, neither Trump nor any other Republican has explained what specifically in the whistleblower complaint they take issue with. Like the bank robber who is now in jail, they may wish nobody had called 911 with an anonymous tip, but they can’t make the evidence disappear.

That brings us to the reason Trump’s defenders are focusing so much of their efforts on identifying the whistleblower: Once the person’s identity is revealed, then they can find something to discredit them with and crank up the character assassination machine, which will then allow them to say that the whole thing was fruit of a poisonous tree and Trump must be found innocent.

It’s the equivalent of Attorney General William P. Barr’s farcical investigation into the FBI’s counterintelligence probe of Russian interference in the 2016 election, the gobsmacking premise of which is basically that the FBI should never have bothered investigating Russian actions in the first place. We all know where Barr is heading: If he can find some trivial instance of procedures not being followed to the letter, he’ll hold it aloft and all Republicans will cry that the fix was in, the “deep state” tried to destroy Trump and we no longer have to worry about what Trump, his family and his campaign did.

That script is precisely what Republicans are hoping for in their quest to unmask the whistleblower. If it turns out the person is a registered Democrat, or their cousin’s husband’s barber donated money to the Clinton campaign, or they once got a parking ticket, Republicans will say “Aha! See, the whole thing is a scam! None of the evidence matters! Now everyone, put your fingers in your ears and say ‘Nanana I can’t hear you’ whenever anyone starts talking about the substantive grounds for impeachment!”

That’s what they’re after, because they understand this simple fact: Trump did exactly what he’s accused of. He attempted to coerce a foreign government into launching a bogus investigation to discredit one of his political rivals, and he had his unhinged “lawyer” manipulating U.S. foreign policy to do it.

If Republicans want to argue that it wasn’t impeachable conduct, they should go ahead and make that case. But they can’t claim it didn’t happen, and no amount of shouting about the whistleblower will change that.

Read more: