WASHINGTON >> A former FBI lawyer intends to plead guilty after he was charged with falsifying a document as part of a deal with prosecutors conducting their own criminal inquiry of the Russia investigation, his lawyer and court documents made public today.

The lawyer, Kevin Clinesmith, 38, who was assigned to the Russia investigation, plans to admit that he altered an email from the CIA that investigators relied on to seek renewed court permission in 2017 for a secret wiretap on former Trump campaign adviser Carter Page, who had at times provided information to the spy agency. Clinesmith’s lawyer said he made a mistake while trying to clarify facts for a colleague.

President Donald Trump immediately promoted the plea agreement as proof that the Russia investigation was illegitimate and politically motivated, opening a White House news conference by calling Clinesmith “corrupt” and the deal “just the beginning.”

Trump has long been blunt about viewing the investigation by the prosecutor examining the earlier inquiry, John Durham, as political payback whose fruits he would like to see revealed in the weeks before the election.

Attorney General William Barr has portrayed Durham’s work as rectifying what he sees as injustices by officials who sought in 2016 to understand links between the Trump campaign and Russia’s covert operation to interfere in the election.

Clinesmith had written texts expressing opposition to Trump. But prosecutors did not reveal any evidence in charging documents that showed Clinesmith’s actions were part of any broader conspiracy to undermine Trump. And the Justice Department’s independent inspector general, Michael Horowitz, has found that law enforcement officials had sufficient reason to open the Russia investigation, known inside the FBI as Crossfire Hurricane, and found no evidence that they acted with political bias.

As part of their efforts to dissuade prosecutors from charging Clinesmith, his lawyers argued that his motives were benign, and other evidence indicated that he had not tried to hide the CIA email from his colleagues.

“Kevin deeply regrets having altered the email,” Clinesmith’s lawyer, Justin Shur, said in a statement. “It was never his intent to mislead the court or his colleagues, as he believed the information he relayed was accurate. But Kevin understands what he did was wrong and accepts responsibility.”

Clinesmith, who resigned over the matter last year, was expected to be charged in federal court in Washington with a single felony count of making a false statement. A spokesman for Durham declined to comment.

Barr had previewed the agreement on Fox News’ “Hannity” on Thursday night, announcing that a development would occur in the investigation today. “It’s not an earth-shattering development, but it is an indication that things are moving along at the proper pace, as dictated by the facts in this investigation,” he said.

It is highly unusual for law enforcement officials to publicly discuss ongoing investigations, but Barr has long made clear his distaste for the Russia investigation and his view that Durham would remedy any issues with it.

Although the sprawling Russia investigation that was eventually run by a special counsel, Robert Mueller, uncovered the Kremlin’s complex operation to subvert the election and the Trump campaign’s expectation that it would benefit from foreign involvement, Republicans have seized on a narrow aspect of the inquiry — the investigation into Page — in a long-running quest to undermine it.

An energy executive with contacts in Russia, Page was brought on to advise the Trump campaign in the spring of 2016 as the candidate was solidifying his unexpected lead in the Republican primary race and scrambled to cobble together a foreign policy team.

Investigators eventually suspected that Russian spies had marked Page for recruitment. They first obtained permission from the secretive Foreign Intelligence Surveillance Court in October 2016 to wiretap Page, who had left the campaign by then, and the court agreed to extend the order three times in subsequent months.

After Republicans raised concerns about the information that investigators relied on to seek the court’s approval to eavesdrop on Page, Horowitz began an exhaustive review of the process.

In a report made public last year, Horowitz revealed that the applications were riddled with serious errors and omissions. Among other things, he had learned of a troubling series of events in which Page’s association with the CIA was not accurately conveyed to the Justice Department and ultimately kept from the judges who approved the surveillance warrants.

Page had for years provided information to the CIA about his contacts with Russian officials. In CIA jargon, he was known as an operational contact — someone who agrees to be debriefed by agency personnel but cannot be assigned to collect information.

That relationship might have given law enforcement officials reason to be less suspicious of him. And the FBI was told about it: A CIA lawyer provided a list of documents in the August 2016 email at the heart of the case against Clinesmith that explained Page’s relationship with the agency.

But an FBI case agent who learned about Page’s ties to the CIA played them down while preparing the first wiretap application, according to the inspector general’s report. At the time, Clinesmith was not involved in determining whether Page was a CIA source, people familiar with the case said.

But later in 2017, a supervisory FBI agent handling the third and final renewal application asked Clinesmith for a definitive answer on whether Page had been an agency source, according to Horowitz’s report.

Clinesmith incorrectly said that Page was “never a source” and sent the CIA’s information to the supervisor. He altered the original email to say that Page had not been a source — a material change to a document used in a federal investigation.

The agent relied on the altered email to submit the application seeking further court permission to wiretap Page, the inspector general wrote. By changing the email and then forwarding it, Clinesmith misrepresented the original content of the document, which prosecutors said was a crime.

Clinesmith did not change the document in an attempt to cover up the FBI’s mistake. His lawyers argued that he had made the change in good faith because he did not think that Page had been an actual source for the CIA.

Clinesmith’s lawyers also argued that their client did not try to hide the CIA email from other law enforcement officials as they sought the final renewal of the Page wiretap. Clinesmith had provided the unchanged CIA email to Crossfire Hurricane agents and the Justice Department lawyer drafting the original wiretap application.

Clinesmith had also urged investigators to send any information about an informant’s meeting in October 2016 with Page, including any exculpatory statements, to the Justice Department lawyer drafting the wiretap application. Clinesmith said this was “probably the most important” information to provide to the lawyer drafting the wiretap application.

Clinesmith was among the FBI officials whom Mueller removed from the Russia investigation after Horowitz found messages they had exchanged expressing political animus against Trump.

Shortly after Trump’s election victory, Clinesmith texted another official, “I honestly feel like there is going to be a lot more gun issues, too, the crazies won finally. This is the Tea Party on steroids. And the GOP is going to be lost.”

In another text, he wrote, “Viva le resistance.”

Clinesmith told the inspector general that he was expressing his personal views but did not let them affect his work.

Clinesmith also argued against the prospect of wiretapping another former Trump campaign adviser, George Papadopoulos, who served two weeks in jail on a charge of lying to the FBI, according to the Horowitz report. The inspector general said the bureau never sought to surveil him.

The prosecution of Clinesmith is just one aspect of Durham’s expansive investigation. He has also been examining the intelligence community’s most explosive conclusion about Russian interference in the 2016 election: that President Vladimir Putin intervened to benefit Trump.

Durham has also been scrutinizing the FBI’s use in the wiretap applications of a notorious dossier that was compiled by a British former intelligence officer, Christopher Steele.

“The FBI has been, and will continue to be, fully cooperative with Mr. Durham’s review,” a press representative for the bureau said in a statement. “This includes providing documents and assigning personnel to assist his team.”

Durham, who has previously investigated FBI and CIA abuses, has not tipped his hand at what he has found, though Barr has said some of the findings are “troubling.” Durham has said in a rare statement that he disagreed with some of Horowitz’s conclusions about how and why the FBI opened the inquiry in the summer of 2016.