Donald Trump’s July 25 phone call with Volodymyr Zelensky showcased the president’s obvious corruption, underscoring the lengths to which he’ll go to maintain power—in this case, by pressuring Ukraine to dig up dirt on a political rival. But the shady conversation also served as a reminder of something else: That the president’s bottomless appetite for conspiracies informs, and exacerbates, his worst tendencies.

In his call with the Ukranian president, Trump pressed not only for a probe into Biden and his son, Hunter, but also into CrowdStrike, an American cybersecurity firm that helped the Democratic National Committee investigate its 2016 email hack. Trump appeared to believe that the DNC server might be hidden somewhere in the country. “The server, they say Ukraine has it,” Trump told Zelensky, according to a rough readout of the call. But former Homeland Security Secretary Tom Bossert refuted the conspiracy theory on Sunday, telling George Stephanopoulos that the crackpot narrative embraced by Trump and Rudy Giuliani doesn’t have a shred of merit. “It’s not only a conspiracy theory,” Bossert said. “It is completely debunked.”

The theory on the right is that Ukraine is responsible for the DNC hack, and that Kiev subsequently framed Russia for the whole ordeal, perhaps with the help of Democrats themselves. As the New York Times reported Sunday, Bossert and other United States officials repeatedly told Trump that there was nothing to it, including in conversations just before his inauguration and shortly thereafter. Still, it was reportedly a “constant struggle” to convince Trump that Ukraine wasn’t responsible, a former senior administration official told the Times. Just when it seemed like the truth might sink in, the president would talk to friends like Giuliani and reverse course. “At this point, I am deeply frustrated with what [Giuliani] and the legal team is doing and repeating that debunked theory to the president,” Bossert said Sunday. “It sticks in [Trump’s] mind when he hears it over and over again.”

One former aide blamed Giuliani’s firm belief in the theory for the mess in which Trump now finds himself. The lawyer, the aide told the Times, would “feed Trump all kinds of garbage” that created “a real problem for all of us.” In an interview on Sunday, former Ukranian head prosecutor Yuri Lutsenko said he saw no evidence of wrongdoing in Hunter Biden’s case. “I told him I could not start an investigation just for the interests of an American official,” Lutsenko said of his dealings with Giuliani.

The abuse of presidential power apparent in the rough transcript of Trump’s Zelensky call and the whistleblower complaint declassified last week have sparked increasing support for his impeachment. According to a new CBS News poll, more than half of Americans now back the inquiry Nancy Pelosi officially launched last week. Still, despite concern from some Republicans about the phone call and the president’s unbalanced behavior, most in the GOP have either stayed on the sidelines or gone to absurd lengths to defend him. “Why would we move forward with impeachment?” House Minority Leader Kevin McCarthy said in an embarrassingly ineffectual attempt to dismiss allegations of Trump’s wrongdoing on 60 Minutes Sunday. “There’s not something that you have to defend here.”

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