The Republican chairman of the Senate Homeland Security and Governmental Affairs Committee announced Monday that he has issued a subpoena to the FBI for records related to the bureau’s probe of Russian interference in the 2016 election.

The subpoena was the first issued by the committee as part of its examination of the origins of the FBI’s Russia investigation and former vice president Joe Biden and Ukraine. Democrats have condemned the inquiry, saying it risks laundering Russian disinformation into the United States through the Senate ahead of the 2020 presidential election.

A copy of the subpoena, which was first reported by Politico, was released by the committee Monday, along with a voluminous open letter from Johnson defending the GOP inquiry and attacking his Democratic critics.

“Democrats have initiated a coordinated disinformation campaign and effort to personally attack Senate Finance Committee Chairman Charles Grassley and me for the purpose of marginalizing the findings of our investigations,” Johnson wrote. “Chairman Grassley and I will not be deterred by the false accusations despicably being made by individuals with strong political biases and motivations.”

The subpoena issued to the FBI on Aug. 6 includes a request for “all records related to the Crossfire Hurricane investigation,” the code name given to the FBI investigation into whether any Trump advisers were involved in Russian election interference in 2016.

The subpoena specifically asks for all records provided or made available to the Justice Department’s inspector general, who conducted his own examination of the FBI’s Russia investigation, including its requests for surveillance warrants of Carter Page, who served that year as a foreign policy adviser to the Trump campaign.

The inspector general found serious problems with the FBI’s handling of requests for the surveillance warrants. Overall, however, the report did not find evidence that the 2016 inquiry was unjustified or tainted by bias. “We did not find documentary or testimonial evidence that political bias or improper motivation influenced the decisions” by the bureau, the report concluded.

Attorney General William P. Barr took rare public exception to that part of the inspector general’s report, saying that he thought the Russia investigation was launched on the “thinnest of suspicions.”

Johnson’s subpoena to the FBI also requests all documents related to requests to the General Services Administration for Trump presidential transition records.

The FBI said in a statement it has received the subpoena and has “already been producing documents and information to the Senate Homeland Security Committee, which are directly responsive to this subpoena. As always, the FBI will continue to cooperate with the Committee’s requests, consistent with our law enforcement and national security obligations.”

In his letter Monday, Johnson also took issue with a recent Washington Post op-ed written by Sen. Richard Blumenthal (D-Conn.) that suggested his inquiry into Ukraine may have resulted from “theories peddled by Kremlin proxies.”

Blumenthal referred in his piece to Andrii Derkach, a Ukrainian lawmaker previously affiliated with a Russian-leaning party, who told The Post that he had sent documents to Johnson’s and Grassley’s Senate committees. Both committees denied that they had accepted information from him.

On Friday, a top U.S. intelligence official named Derkach as part of Russia’s efforts to undermine Biden in advance of November’s election.

In his letter Monday, Johnson said Blumenthal’s claim that the committee was using documents from Derkach was false.

“Let me be clear: The investigation by my committee of allegations of conflicts of interest within the Obama administration related to Ukraine policy and of allegations of corruption within the Obama administration affecting the 2016 election is focused on documents and officials from U.S. government agencies and a U.S. Democrat-linked lobbying firm,” he said. “We have not taken, nor do we possess, the documents from Ukrainians that Democrats keep claiming.”

In a statement, Blumenthal spokesperson Maria McElwain said that “Senator Johnson’s alternative history of the investigation into Russian efforts to meddle in the 2016 election reads like a piece of Putin propaganda.

“If Senator Johnson doesn’t like how it looks when he pursues politically-motivated investigations in an election year, he should cease his efforts to obtain information from Russian-linked Ukrainian operatives peddling disinformation to interfere with our elections,” she said.

Johnson’s subpoena came as the GOP head of the Senate Judiciary Committee raised new allegations about a different aspect of the 2016 Russia probe.

On Sunday, Sen. Lindsey O. Graham (R-S.C.) claimed that a newly declassified document showed that in 2018, FBI officials lied to the Senate Intelligence Committee about the reliability of information in a dossier of Trump’s alleged Russia ties compiled by former British spy Christopher Steele.

On Monday, Graham sent a letter to FBI Director Christopher A. Wray, demanding he tell Graham the names of the FBI officials who prepared talking points and briefed the panel, and provide the Judiciary Committee with any related documents and materials that were shared with Congress.

But Graham took those steps without consulting with the Senate Intelligence Committee itself.

Neither Republicans nor Democrats on that panel believe FBI officials lied to them as Graham alleged, since the information they presented was cleared by people at the highest levels of the Justice Department, according to people familiar with the Senate Intelligence Committee’s investigation, who spoke on the condition of anonymity to describe internal discussions.

“We are focused on getting to the bottom of how Crossfire Hurricane got so off track and will vigorously continue to pursue the facts on what actually happened,” said Taylor Reidy, a spokeswoman for Graham.

The Senate Intelligence Committee is expected to put out the fifth and final volume of its report into Russian interference in the 2016 election later this month, which will clock in at just under 1,000 pages, according to people familiar with the investigation.

The volume is expected to contain substantial criticism of Steele’s dossier and how the FBI and DOJ handled it, according to the people.

Devlin Barrett contributed to this report.