President Donald Trump and his congressional allies have a bizarre game plan for this week’s impeachment hearings. First, they’re going to argue that when Trump pressed Ukraine to investigate his Democratic opponents—in particular, former Vice President Joe Biden—Trump’s goal was to fight corruption, not to hurt Biden or the Democrats. Then, to prove that it wasn’t about smearing Biden or the Democrats, Trump and his allies will use the hearings to smear Biden and the Democrats.

The first half of this self-refuting strategy—the part about corruption—makes sense. If Trump had pushed Ukraine to crack down on corruption generally, and if Biden were one of the targets caught up in that anti-corruption drive, that would be a side effect of normal U.S. policy, not an abuse of power. That version of events isn’t true: Biden did nothing wrong, and Trump targeted him specifically. But if it were true, Trump would be innocent. That’s why Republican senators peddled this theory on the Sunday talk shows. Trump “was concerned about corruption,” said Sen. Ron Johnson of Wisconsin. Sen. Lindsey Graham of South Carolina claimed that Trump “asked the Ukrainian president to look in corruption” only because “corruption is rampant in the Ukraine.” Sen. John Kennedy of Louisiana suggested that Trump “asked for an investigation of possible corruption” by someone who just “happens to be a political rival.”

These senators are betting that no one can prove what Trump’s real motive was. To do so, investigators would “have to get into the mind of Trump and his advisers,” argued Sen. Rand Paul of Kentucky. “There’s no way.” In the absence of proof, Paul concluded, dueling theories of Trump’s intent would boil down to an irresolvable “partisan debate.” And with 53 Republicans in the Senate, Trump would be acquitted.

There’s so much evidence against Trump that Republican senators keep stumbling into it.

In real life, there are lots of ways to determine a suspect’s motive. Cops and courts do it all the time. In this case, the simplest question is whether Trump sought anti-corruption reforms in Ukraine as a general matter. And the answer is: He didn’t. Testimony, text messages, and a transcript of the president’s July 25 phone call with Ukrainian President Volodymyr Zelensky show that Trump consistently targeted his enemies and ignored corruption.

There’s so much evidence against Trump that Republican senators keep stumbling into it. “Foreign aid, by law, can only go out to countries that are not corrupt,” Paul argued on Meet the Press. “So if you think that a country is acting in a corrupt way, a president can always withhold aid until the corruption is fixed.” That’s true: Under federal law, military aid to Ukraine requires “a certification by the Secretary of Defense … that the Government of Ukraine has taken substantial actions to make defense institutional reforms for purposes of decreasing corruption.” But the Department of Defense provided that certification, in writing, on May 23. Trump ignored the certification and blocked aid to Ukraine anyway.

Johnson, speaking on CNN’s State of the Union, spilled more evidence against Trump. The senator confirmed that on May 23, after a visit to Ukraine, he and other U.S. officials explained to Trump that Zelensky was attacking corruption. Trump was unmoved. According to Johnson, Trump just kept repeating that Ukrainians were “all corrupt.” As to what Trump meant, Johnson offered a clue. “What I have always heard the president consistently concerned about is what happened in 2016,” Johnson reported—apparently referring to Trump’s obsessive and false belief that Ukraine tried to “take me down” in the 2016 election. He paraphrased Trump’s private rants: “How did this false narrative of Russian collusion with my campaign occur? … Why I have been tormented? Why have—where’s this effort to sabotage my presidency?”

Every time Trump opens his mouth, he gives away the game: “Corruption” is his code for smearing Democrats. “We are looking for corruption,” the president declared on Friday, speaking about Ukraine. “We’re giving hundreds of millions of dollars, and we’re looking for corruption. And all you have to do is take a look at Biden, and you’ll see tremendous corruption.”

If Republicans seriously believed that Trump cared about corruption, they’d try to produce evidence that he used his leverage with Ukraine to seek institutional reforms or prosecutions that didn’t benefit him personally. But their proposed list of witnesses for the impeachment hearings, delivered on Saturday in a letter to House Intelligence Committee Chairman Adam Schiff, conveyed no interest in such questions. The letter focused entirely on Biden, his son Hunter, and other Democrats.

Sunday’s TV performances continued this farce. Kennedy, speaking on Face the Nation, said the impeachment debate boiled down to two questions. One was whether Trump had sought to investigate corruption or a political rival. The second, according to Kennedy, was “What did Mr. Hunter Biden do for the money?” Paul, in his interview on NBC, agreed. “If you can’t call Hunter Biden,” said Paul, “that’s not even really a trial.” Graham, appearing on Fox News, issued the same demand. “Denying the Republicans the ability to trace the Hunter Biden conflict-of-interest storyline,” he argued, “is basically denying the president the ability to defend himself.”

Think about that statement. If Trump’s defense rests on rehashing the Biden “storyline,” what does that say about the GOP’s contention that this was never about politics? It says that contention is a fraud. On Tuesday, Trump all but confessed as much. “As President, I have an ‘obligation’ to look into corruption, and Biden’s actions,” he tweeted. “Both Bidens should be forced to testify in this No Due Process Scam!” The president of the United States, accused of targeting his political opponents for investigation, responds by targeting his political opponents for investigation.

As the hearings proceed, Trump and his allies will rail at Schiff for failing to call Joe Biden, Hunter Biden, and other witnesses Republicans want to use to vilify the Democratic Party. They’ll ignore the evidence that Trump demonstrated no real interest in fighting corruption, and they’ll focus instead on smearing the Bidens. Politically, this cynical campaign might succeed. But morally, it’s self-incriminating. It shows that the GOP’s excuse for acquitting the president—that his pressure on Ukraine wasn’t about partisan politics—is a lie.