Acting FBI Director Andrew McCabe promised senators on Thursday that he will not give the White House updates on the Russia election probe.
He also said President Donald Trump's abrupt firing of James Comey will not disrupt the bureau's investigation.
At the Senate Intelligence Committee hearing, the panel's Vice Chairman, Mark Warner, D-Va., asked McCabe if he would commit to informing the committee of any political interference in the Russia investigation. "I absolutely do," McCabe responded.
"There has been no effort to impede our investigation to date. ... You cannot stop the men and women of the FBI from doing the right thing," McCabe said when Sen. Marco Rubio, R-Fla., asked if the firing has disrupted any of the FBI's work.
The White House has repeatedly said Comey's abrupt firing on Tuesday had nothing to do with the Russia probe, which Comey explained in March includes investigating any possible links between Trump campaign associates and the Kremlin.
Comey had been set to appear at the already-scheduled hearing on global threats before his ouster.
White House provides multiple explanations for firing
McCabe denied that Comey had lost
"Director Comey enjoyed broad support within the FBI and still does today," McCabe said.
The Trump administration has suggested multiple motives for Comey's termination, including his conduct in the probe into Hillary Clinton's handling of classified information last year and an error in his congressional testimony on the probe last week. However, the timing of the firing — which comes as the bureau is investigating the president's campaign — has raised concerns from lawmakers on both sides of the aisle, including several Senate Republicans.
It has also sparked questions about whether the Trump administration will attempt to derail the probe.
In his letter firing Comey, Trump went out of his way to write that the FBI director told him three times he was not under investigation. Such a statement from Comey would not appear to follow the FBI's protocol, multiple reports said.
Asked Thursday if he knew if Comey told Trump he was not under investigation, McCabe said he could not comment. Later in the hearing, McCabe said he would not give the White House such updates on the investigation.
He called it a "highly significant investigation." The White House has contended that there is nothing underpinning the probe and Americans should move on from it.
McCabe said he was not aware of a reported Comey request for more resources for the probe, adding that he believes it is "adequately" funded.
Democrats have decried the firing and increased their calls for a special prosecutor in the Russia investigation. Most Republican lawmakers, though, have resisted those calls and said that the Senate Intelligence Committee's probe into Russian interference is adequate.
Trump has repeatedly denied that his campaign colluded with Russia, and has even suggested that Moscow may not be responsible for
McCabe, who joined the FBI 20 years ago and became deputy director last year, is respected within the bureau. Comey enjoyed similar popularity among the rank and file of the FBI.