Deputy Attorney General Rod Rosenstein (right) responded to questions about the role FBI agent Peter Strzok played in special counsel Robert Mueller's probe. | John Shinkle/POLITICO Mueller took 'steps' to shield Russia probe from bias, DOJ says Republicans feel an FBI agent who sent numerous anti-Trump texts may have tainted the investigation.

Special counsel Robert Mueller has taken "appropriate steps" to ensure that anti-Trump bias hasn’t infected his investigation of Russian interference in the 2016 presidential election, according to his boss, Deputy Attorney General Rod Rosenstein.

“Director Mueller has vast experience both as a prosecutor and as supervisor of the FBI,” Rosenstein told lawmakers Thursday during a House Judiciary Committee hearing. “I can assure you that he understands the importance of considering any credibility issues."


Rosenstein was responding to questions from Rep. John Ratcliffe (R-Texas) about the role that FBI counterintelligence agent Peter Strzok played in Mueller's probe, which is examining whether the Trump campaign coordinated with Moscow on its election meddling efforts. Strzok sent dozens of text messages to a fellow FBI official assailing then-candidate Donald Trump and expressing hostility to a potential Trump presidency. Strzok was briefly assigned to Mueller's investigation but was removed shortly after an internal Justice Department watchdog uncovered the texts.

Rosenstein on Thursday said Mueller would have to assess the credibility of any witness or evidence that was produced by Strzok in the investigation.

“Director Mueller knows that,” he said.

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In the exchange, Ratcliffe revealed that during a closed-door meeting between Strzok and lawmakers, Strzok said Mueller never questioned him about whether any of his investigative decisions were tainted by bias. Ratcliffe said Strzok described a 10- to15-minute conversation with Mueller after which the special counsel ultimately removed him from the case.

Strzok told lawmakers that “neither special counsel Mueller nor anyone on his team asked him about the texts or his expressed hatred of Donald Trump,” Ratcliffe said.

Rosenstein emphasized that he learned about Strzok's text messages at the same time Mueller did and that the discovery came while the inspector generally was actively investigating the matter. Though Mueller acted quickly to remove Strzok, Rosenstein said they deferred to the inspector general's probe.