How do you defend the indefensible? The task proved difficult even for President Donald Trump’s staunchest supporters over the weekend, as the media pressed them to explain why Trump pressured Ukrainian President Volodymyr Zelenskiy in July to investigate Joe Biden and his son.

House Minority Leader Kevin McCarthy tried to claim on CBS’ 60 Minutes that Trump didn’t actually ask Zelenskiy for a “favor,” only for host Scott Pelley to read the portion of the memo where Trump does just that. Minority Whip Steve Scalise claimed on NBC’s Meet the Press that Trump’s request for a favor proved his commitment to learning the whole truth about foreign interference in the 2016 election. Stephen Miller, Trump’s top domestic policy adviser, offered only conspiracy theories when pressed for straight answers by Fox News anchor Chris Wallace.

There’s nothing new about Trump’s surrogates on TV struggling to defend his conduct, of course. But their flailing performance this weekend highlights a deeper problem for the president. If the House impeaches him, and the Senate holds a trial, Trump will have to make an affirmative case for acquittal to 100 senators, many of whom hold public or private concerns about his fitness to be president. So far, Trump’s defenders haven’t even come close to making a convincing argument in his favor.

The biggest weakness in Trump’s defense is that—as the White House’s own summary transcript of the Zelenskiy call proves—he actually did what Democrats allege: abuse his power by urging a foreign government to undermine his domestic political rivals. McCarthy tried first to deny that anything had happened, and then insisted that it didn’t have to be defended at all. “What do you make of this exchange?” Pelley asked McCarthy. “President Zelenskiy says, ‘We are almost ready to buy more Javelins from the United States for defense purposes.’ And President Trump replies, ‘I would like you to do us a favor though.’” McCarthy’s first response was denial. “You just added another word,” he replied.

Pelley had not added another word. “No, it’s in the transcript,” he said. “He said, ‘I’d like you to do a favor though’?” McCarthy asked. “Yes, it’s in the White House transcript,” Pelley confirmed. McCarthy then brushed off the exchange by faulting Barack Obama for not selling anti-tank weapons to Ukraine in the first place. His answers only grew more inscrutable. “Why would we move forward with impeachment?” McCarthy argued. “There’s not something that you have to defend here.” Michigan Representative Justin Amash, who left the GOP in July, tweeted that McCarthy’s interview “again displays his unique brand of incompetence and dishonesty.”