Deputy Attorney General Rod Rosenstein told the House Judiciary Committee on Wednesday he has seen no reason to fire Mueller thus far.
"If there were good cause, I would act. If there were no good cause, I would not," Rosenstein told the committee.
When asked by the committee's top Democrat, Rep. Jerry Nadler, if he's seen a cause to fire Mueller, Rosenstein responded: "No."
And later when asked by another member of the committee if President Donald Trump has asked him to remove Mueller from the investigation, he said no one has asked him to do that.
"I am not going to be discussing my communications with the President but I can tell you that nobody has communicated to me the desire to remove Robert Mueller," he said.
He also said he's not afraid of Trump firing him when asked.
"No I'm not," he said.
Wednesday's hearing gave lawmakers the opportunity to grill Rosenstein publicly on his views of everything from Trump's cable news-fueled rages about the Justice Department's handling of various investigations to Mueller's investigation.
Rosenstein -- who retains oversight of Mueller's investigation since Attorney General Jeff Sessions recused himself from all 2016 campaign-related probes -- has managed to keep a low profile since his front and center role in the firing of FBI Director James Comey back in May.
During the hearing, Rosensetin praised Mueller for his work in the special counsel, saying there was no one better qualified for the job.
"I believe based on his reputation, his service, his patriotism, and his experience with the department and with the FBI, I believe he was an ideal choice for this task," he told the committee.
GOP Rep. Lamar Smith asked Rosenstein about Mueller asking for clarification about the scope of his investigation, whether Mueller may be "casing too wide of a net" in what he's looking into.
"There are a lot of media stories speculating about what the special counsel may or may not be doing," Rosenstein responded. "I know what (Mueller is) doing. I'm appropriately exercising my oversight responsibilities. So I can assure you that the special counsel is conducting himself consistently with our understanding about the scope of his investigation."
And on whether the committee could investigate Trump for obstruction of justice with regards to the Russia investigation, Rosenstein said Mueller's team can investigate "anybody."
"It authorizes him to investigate anybody who there is predication to believe obstructed justice," he said, later adding when asked to clarify on the President, "It would include anybody who was suspected of obstructing justice."
Bias versus politics
What might normally have been a routine oversight hearing before the House Judiciary Committee for Rosenstein is now taking on a new focus in light of a report late Tuesday evening of roughly 375 politically-charged text messages
exchanged between two top FBI employees that were turned over to congressional investigators.
In his opening statement, Committee Chairman Bob Goodlatte previewed he would be asking Rosenstein about about Peter Strzok,
one of the FBI's top counterintelligence experts, and FBI lawyer Lisa Page exchanged a running commentary of criticism of then-presidential candidate Trump via text message for months.
Stzrok was immediately removed from special counsel Robert Mueller's team this past summer after the text messages were uncovered through an internal investigation at the Justice Department.
"Reports on the political predisposition, and potential bias, of certain career agents and department lawyers on Special Counsel Mueller's team are deeply troubling to all citizens who expect a system of blind and equal justice," Goodlatte said in his opening statement. "We are now beginning to better understand the magnitude of this insider bias on Mr. Mueller's team."
Later in the hearing, GOP Rep. Steve Chabot asked Rosenstein whether the political opinions of the members of the FBI investigation would influence the outcome.
"I think it's important to recognize that when we talk about political affiliation -- that all demonstrates political affiliation -- the issue of bias is something different," Rosenstein responded. "I have discussed this with Director Mueller ... We recognize we have employees with political opinions. And it's our responsibility to make sure those opinions do not influence their actions.
He continued: "And so I believe that Director Mueller understands that and he is running that office appropriately, recognizing that people have political views, but ensuring that those views are not in any way a factor in how they conduct themselves in office."
Clinton email probe
During his opening statement, Goodlatte also hinted he would press Rosenstein on appointing a second special counsel "to investigate the improprieties" related to the handling of the investigation into then-Democratic presidential hopeful Hillary Clinton's email probe under then-FBI Director James Comey.
He later asked Rosenstein about the inspector general's investigation into the handling of the email probe.
"Last week, (FBI) Director (Christopher) Wray acknowledged that the normal procedures were not followed with respect to Secretary Clinton's email server," Goodlatte told Rosenstein after his opening statement. "If the inspector general discovers that normal protocol was not followed or that the investigation was closed or otherwise tainted for political purposes, would that be a justification in your mind to reopen the investigation?"
Rosenstein responded he wanted to wait until results from the inspector general's investigation before making a decision on Clinton's emails.
"That's the inspector general's job," Rosenstein responded. "He'll reach his own independent determination. But as you pointed out, my views about it are already known."
Later in the hearing, GOP Rep. Jim Jordan pressed Rosenstein to set up a second special counsel.
"This is unbelievable," he said. "And I'm here to tell you Mr. Rosenstein I think the pubic trust in this whole thing is gone. ... You're the guy in charge. You can disband the Mueller prosecutor and you can do what we've all called for. Appoint a special counsel to look into this."
Rosenstein responded: "I think it's important to understand, congressman, that we have an inspector general who has 500 employees and a $100 million budget, and this is what he does."
This story has been updated.