WASHINGTON — Two Republican senators have made the first known criminal referral in congressional investigations of Russian meddling in the 2016 election, targeting the author of a dossier of allegations about President Donald Trump's ties to Russia.

Senate Judiciary Committee Chairman Chuck Grassley, R-Iowa, and South Carolina Sen. Lindsey Graham said Friday they had referred former British spy Christopher Steele to the Justice Department for investigation about false statements he may have made to the government. Graham is the chairman of a Judiciary subcommittee that is investigating the Russian meddling.

The referral comes after Republicans in Congress have made several attempts in recent weeks to undermine the credibility of special counsel Robert Mueller's investigation, the Justice Department and the FBI, charging there is anti-Trump bias within the ranks of federal agents and prosecutors.

In a cover letter to Deputy Attorney General Rod Rosenstein and FBI Director Christopher Wray released by the committee, the senators say the referral relates to "certain communications between Christopher Steele and multiple U.S. news outlets regarding the so-called 'Trump dossier.'" The rest of the referral is classified and was not released.

Lawmakers cannot prosecute, but generally refer any criminal violations they find to the Justice Department. On Friday, Justice Department spokeswoman Sarah Isgur Flores said the department had received the referral and will review it.

The dossier is a compilation of memos Steele wrote during the 2016 campaign that contained several allegations of connections between Trump and Russia, including that Trump had been compromised by the Kremlin. Trump has called the dossier "phony" and derided it as a politically motivated hit job, and many Republicans in Congress have been focused on discrediting it.

The cover letter does not say who the senators believe Steele lied to, but Grassley said in a statement about the referral that "everyone needs to follow the law and be truthful in their interactions with the FBI."

Republicans have been asking the Justice Department for months whether the dossier was used as part of its initial investigation into Russian interference.

The dossier was turned over to the FBI in 2016, and federal investigators worked to corroborate portions of it. Some of the information was distilled into a summary that then-FBI Director James Comey presented to then-president-elect Trump in January 2017.

More recently, Mueller's investigators interviewed Steele in Europe as part of their probe into Russian election interference and ties between Trump associates and the Kremlin.

"The rule of law depends on the government and all who work on its behalf playing by the rules themselves," Graham said in a statement. "I hope the Department of Justice will carefully review our letter and take appropriate action."

On Friday, Sen. Richard Blumenthal of Connecticut, a Democrat on the Judiciary committee, called the move a partisan effort "aimed at someone who reported wrongdoing, rather than committed it."

"These vaguely stated, secret allegations seem designed more to distract attention from the priority issues for investigation, and discredit the FBI and other law enforcement," Blumenthal said in a statement, noting that the FBI's investigation into Russian interference and the Trump campaign was "triggered by information completely independent" from the dossier, Steele or Fusion GPS, the opposition research firm who hired him.

The Judiciary Committee has not interviewed Steele. A release from the committee said that the referral, which is based on both classified and publicly available information unearthed by investigators, does not pertain to the veracity of claims in the dossier.

"The referral is for further investigation only, and is not intended to be an allegation of a crime," the committee's release said.

A lawyer for Fusion GPS, which was initially paid by a conservative website tied to Republicans and then later by Democrats to carry out the research into Trump, criticized the senators for the referral and also for publicizing it.

"After a year of investigations into Donald Trump's ties to Russia, the only person Republicans seek to accuse of wrongdoing is one who reported on these matters to law enforcement in the first place," said Joshua A. Levy, counsel for Fusion GPS. "Publicizing a criminal referral based on classified information raises serious questions about whether this letter is nothing more than another attempt to discredit government sources, in the midst of an ongoing criminal investigation. We should all be skeptical in the extreme."