House Speaker Mike Johnson (R-LA) is demanding information from U.S. intelligence agencies related to Iran’s hack of former President Donald Trump’s campaign, warning that the U.S. adversary is trying to “tip the election” in favor of Vice President Kamala Harris.

Johnson is requesting information on how the Trump campaign was susceptible to cyberattacks earlier this summer, according to a letter he sent to leaders of the FBI, the Office of the Director of National Intelligence, and the Cybersecurity and Infrastructure Security Agency on Friday. The letter follows a report last week that Iranian hackers disseminated stolen information from the Trump campaign in what Johnson called evidence that Iran is “highly motivated to prevent his election.”