As evidence mounts that President Trump politicized the U.S.-Ukraine relationship for his own benefit, the House Republicans’ plan remains to defend Trump. But how are they going to do that when the State Department witnesses in Wednesday’s impeachment hearing will testify under oath against the president?

Here are a few ways we expect Republicans to try to defend the president — most of which fall short in the face of the evidence against him.

GOP defense No. 1: Democrats can’t prove Trump did it.

In part because, as far as we know, Trump never explicitly said: “Do this for me, and I’ll give you what you want.”

A new memo from House Republican impeachment investigators to GOP lawmakers argues, “The July 25 call summary — the best evidence of the conversation — shows no constitutionality or evidence of pressure.”

That is a very narrow reading of what a quid pro quo is. Trump didn’t have to outright say to Ukraine’s president: Start these investigations to get your military aid. The context surrounding their call matters. Trump ordered the aid frozen a week before the call. Ukrainians had been told by Ambassador to the European Union Gordon Sondland that getting it was contingent on announcing investigations into Democrats. And Taylor testified the Ukrainians had a good sense of this. “I think it was becoming clear to the Ukrainians that, in order to get this meeting that they wanted, they would have to commit to pursuing these investigations,” he said.

According to Republicans’ internal memo, they also want people to take Trump’s and Ukrainian President Volodymyr Zelensky’s word for it that there was no undue pressure. But Trump obviously has a vested interest in not being impeached, and Zelensky has an interest in not upsetting the United States by accusing Trump of wrongdoing.

GOP Defense No. 2: These witnesses don’t have firsthand knowledge of what Trump wanted

This is true. Acting Ukraine ambassador William B. Taylor Jr. and State Department official George Kent were regularly talking to people who listened in on the call with Ukraine’s president and found it troubling, or who heard Trump’s appointees say they offered Ukraine a quid pro quo. Taylor’s testimony was so precise and detailed that someone with firsthand knowledge of what Trump wanted revised his testimony to acknowledge a quid pro quo. Sondland said he had “refreshed my recollection” and remembered telling Ukraine it would get the aid when it announces the investigations Trump wants.

GOP Defense No. 3: What about the Bidens? Democrats and Russia?

This line of defense will muddy the waters on who’s being investigated. During closed-door testimony, Republican lawmakers asked witnesses about the Steele dossier related to the Russia investigation, or tried to allege that those testifying were part of the deep state undermining Trump, or asked whether Trump was right to accuse the Bidens of corruption in Ukraine since Hunter Biden served on the board of a Ukrainian energy company.

This is the distraction method. It’s a way for Republicans to both question the integrity of witnesses and distract from the central allegations these witnesses are making: that Trump tried to force another country to help his reelection.

GOP defense No. 4: The quid pro quo wasn’t successful.

This defense manifests in two ways: 1) that Trump and his White House weren’t competent enough to pressure Ukraine and 2) that Ukraine ultimately got its aid. “President Trump met with President Zelensky and U.S. security assistance flowed to Ukraine in September 2019 — both of which occurred without Ukraine investigating President Trump’s political rivals,” the GOP memo defending Trump reads.

But as Jessica Levinson, a law professor at Loyola University in Los Angeles, told me: A quid pro quo doesn’t have to be successful to be wrong. It’s the attempt to hold back something you shouldn’t hold back that makes it extortion.

GOP defense No. 5: Democrats are partisan and trying to undermine Trump any way they can.

This is harder to refute because partisanship is in the eye of the beholder. What we can say is that to the extent there is any precedent for impeachment, Democrats haven’t broken it to investigate Trump.