A newly obtained trove of internal emails from the FBI agents behind the 2022 arrest of the White House trade advisor, Peter Navarro, may be evidence of longstanding “political rot” within the bureau, Senator Grassley, a Republican of Iowa, claims. 

“The American people have a right to know as much as possible regarding the internal Biden Justice Department and FBI process to determine where to allocate taxpayer resources to investigate and prosecute former Trump officials,” Mr. Grassley writes in a letter to Attorney General Bondi and the FBI director, Kash Patel. 

Mr. Navarro, 75, a fierce Trump loyalist known for his hard line on tariffs, served as a top trade advisor in President Trump’s first administration. After the 2020 election, he was a strong backer of Mr. Trump’s contention that the election was stolen, and is said to have been one of the voices who urged Mr. Trump to tell Vice President Pence not to certify the election. 

In 2022, he was charged with — and later convicted of — contempt of Congress for refusing to cooperate with the Democrat-controlled January 6 committee. He served four months in prison. A few months after his release, Mr. Trump appointed him to a senior trade role in his second administration. 

Mr. Navarro was vocal about what he felt was his persecution by President Biden’s Department of Justice, and the evidence laid out by Mr. Grassley on Friday seeks to prove the point. In an FBI email chain sent among agents in the Washington, D.C., field office with the subject line “Re: Content of Congress cases update,” from May 2022, Special Agent Walter Giardina tells a group of agents that the justice department is “not intending to prosecute [former White House Chief of Staff Mark] Meadows and [former White House Deputy Chief of Staff Dan] Scavino. This decision is based on their White House positions and prior DOJ opinions,” according to the email.

“They would like to charge Navarro in the next two weeks, however,” Mr. Giardina, who includes a list of next steps they’d need to accomplish, such as needing to “locate him” and preparing a search warrant for his phone and Apple iCloud account, writes.

The following day, Mr. Giardina, who “received an award for his work investigating  President Trump as part of Mueller’s team” that he displayed in his office, sent an email update to the group, saying the justice department “would like Navarro indicted on June 2,” according to the email.

Supervisory Special Agent Blaire Toleman forwarded this email to Assistant Special Agent in Charge Tim Thibault, of the Washington, D.C., field office, whom Mr. Grassley described as a “former anti-Trump FBI official.”

In his reply, Mr. Thibault wrote, “Wow. Great.”

“Instead of focusing on the rampant cases of murder and rape perpetrated against everyday Americans, personnel in the FBI’s Washington Field Office and D.C. U.S. Attorney’s Office were obsessing over ways to target President Trump and his allies. Their conduct is disgraceful and un-American,” Mr. Grassley said in a statement.

Mr. Giardina and another FBI agent arrested Mr. Navarro at Reagan National Airport in June 2022 as he was about to board an American Airlines flight to Nashville. Mr. Navarro referred to both agents as “kind Nazis” and asked, “How could you live with yourselves?” according to an FBI document.

Mr. Navarro was found guilty of two counts of criminal contempt of Congress and served four months at a federal prison in Miami. President Trump, who called Mr. Navarro a “man who was treated horribly by the Deep State, or whatever else,” named him trade counselor in December 2024.

In his letter to Mr. Patel and Ms. Bondi, Mr. Grassley requested they search  classified and unclassified records, including communications, belonging to Messrs. Thibault, Toleman, and Giardina and provide them to their offices “to develop a complete understanding of all efforts within the Biden Justice Department and FBI to investigate and prosecute President Trump and his White House staff.” 

Mr. Thibault is a deeply unpopular figure with the Trump administration and Republican lawmakers alike, Mr. Grassley chief among them, who have accused him of partisanship. In 2022, Mr. Grassley, using FBI whistleblower testimony, accused Mr. Thibault of attempting to thwart investigations into Hunter Biden’s business dealings. Last year, Mr. Grassley said Mr. Thibault violated the Hatch Act by engaging in “prohibited political activity on social media” after he retweeted an article, with the headline “Donald Trump Is a Broken Man,” that had been shared by the Lincoln Project, an anti-Trump group.

At the time, Mr. Thibault, through his attorneys, denied the allegations, saying he was “not involved in any decisions related to any laptop that may be at issue in that investigation.” Mr. Thibault was reportedly fired from the FBI in 2022 for violating the Hatch Act, despite his maintaining he voluntarily retired from his role.

Earlier this year, Mr. Grassley released a series of “sensitive” messages that were sent from Mr. Thibault’s FBI account, including a nude picture of Mr. Thibault’s girlfriend.

The FBI did not respond to requests for comment.