Sen. Chuck Grassley (R-Iowa) blasted the media Monday for its recent coverage of the hearsay accusation that President Donald Trump asked Ukraine leaders to investigate his political opponents.

Grassley criticized the media for engaging in “rampant speculation” over a July phone call between President Donald Trump and Ukrainian President Volodymyr Zelensky. A person the media is calling a “whistleblower” who has no direct knowledge of the call, according to their own reports, claimed that Trump requested the Ukrainian president investigate 2020 Democratic front-runner and former vice president Joe Biden and his son Hunter over business dealings with a Ukrainian gas company. Grassley warned that such speculation is what led to a three-year investigation into Russian collusion with the Trump campaign in 2016 that turned out to be a mainstreamed conspiracy theory.

“Rampant speculation by politicians and the media is not helpful,” Grassley said in a statement. “That’s how the false Russia collusion narrative took root. Let’s not repeat the mistakes of the past.”

Grassley asserted that while the intelligence inspector general’s ruling that the complaint was credible and urgent should not be disregarded, Congress still lacks enough information to make its own determination .

“The Inspector General plays an important role in this process, so overruling his assessment shouldn’t become the norm,” Grassley said. “In this case, we simply don’t yet have enough facts to reach an informed conclusion.”

Grassley also emphasized the importance of transparency throughout the process without compromising sensitive information.

“Transparency is always the best policy so long as we don’t endanger national security,” Grassley said.

The statement comes as media are whipping up a frenzy about a conversation between Trump and Volodymyr that echoes the pattern of charges made against the president three years ago when Trump’s political opponents wrongfully accused the president of conspiring with the Russian government to win the 2016 presidential election.

Earlier this month, Intelligence Community Inspector General Michael Atkinson determined that a whistleblower complaint filed against the president over the phone call was both “credible” and “urgent,” although officials at the Department of National Intelligence have split with the Inspector General and refused to release the complaint to Congress. That’s because, as The Federalist’s Erielle Davidson reported, the “credible” complaint is based on secondhand rumors: “According to an official briefed on the matter, the whistleblower ‘didn’t have direct knowledge of the communications.’ Instead, the information in the complaint apparently came from ‘learning information that was not obtained during the course of their work.'”

Regardless, Democrats in Congress and on the campaign trail running to challenge Trump next fall have been quick to use the uncorroborated claims to fuel their persistent calls for the president’s impeachment while new information emerged Monday that the whistleblower did not actually have “firsthand knowledge” of the phone call.