The House Intelligence Committee led by Rep. Devin Nunes (R., Calif.) is expanding its investigation into the FBI and Department of Justice's handling of an ongoing probe into alleged collusion between the Trump campaign and Russia, according to a letter sent Thursday by Nunes to Deputy Attorney General Rod Rosenstein.

Nunes, who spoke by phone with Rosenstein Wednesday evening, ordered the agencies to comply with subpoenas compelling it to produce fully unredacted records of conversations that could shed light on accusations the FBI pursued the investigation in a partisan and unfair manner, according to the letter, a copy of which was obtained by the Washington Free Beacon.

In addition to records and text messages, the House Intelligence Committee has requested interviews with several key FBI officials who have been accused of mishandling the investigation in order to fuel discord in the Trump administration.

The bulk of these documents and records must be handed over by Friday, according to the latest communication from Nunes.

The letter is the second in an escalating effort by the House Intelligence Committee to unearth information pertaining to allegations that the Russia probe was spearheaded by anti-Trump elements in the FBI and was mishandled at various junctures.

The committee also is seeking to determine how much the FBI relied upon and potentially helped disseminate an anti-Trump intelligence dossier produced by the research firm Fusion GPS. [Disclosure: The Washington Free Beacon was once a client of Fusion GPS. That relationship ended in January 2017. For more information, see here.]

"The materials we are requesting are vital to the Committee's investigation of potential abuses into intelligence and law enforcement agencies' handling of the Christopher Steele dossier," Nunes writes in the letter. "The Committee is extremely concerned by indications that top U.S. Government officials who were investigating a presidential campaign relied on unverified information that was funded by the opposing political campaign and was based on Russian sources."

Several key FBI officials will be forced to testify before the Intelligence Committee this month, including former DOJ Associate Deputy Attorney General Bruce Ohr; FBI Supervisory Special Agent Peter Strzok; former FBI General Counsel James Baker; FBI Attorney Lisa Page; FBI Attorney Sally Moyer; FBI Assistant Director Greg Brower; FBI Assistant Director Bill Priestap; and FBI Special Agent James Rybicki.

Fusion GPS recently admitted that it hired the Bruce Ohr's wife, Sally, to investigate Trump, a potential conflict of interest.

The testimony of Strzok also is being viewed as important in light of revelations he exchanged scores of text messages highly critical of President Trump, a disclosure that has fueled accusations of bias.

As part of Congress's effort to investigate the Strzok matter, the committee is forcing the FBI to hand over another 9,500 text messages between Strzok and his mistress, FBI Attorney Lisa Page.

The FBI is said to be continuing its search for additional messages Strzok may have sent.

The Intelligence Committee will also look at records, currently being researched by the DOJ, that shed light on an April 2017 meeting between DOJ Attorney Andrew Weissman—now part of Robert Mueller's Special Counsel—and various parties in the media.

These documents must be produced by Thursday, Jan. 11, according to Nunes' letter.

"Going forward," Nunes writes, "it's crucial that we memorialize our conversations on this issue, and that we're as transparent as possible with the American people, who deserve answers to the questions the Committee is investigating."