Incoming House Intelligence Committee Chairman Adam Schiff said Democrats were prepared to challenge acting Attorney General Matthew Whitaker's legitimacy in overseeing the special counsel Robert Mueller's probe.

Speaking on Sunday's "Meet the Press," Schiff said if Whitaker did not recuse himself from the investigation, he would be "called to answer" by Democrats' full discoveries about any "commitments to the president" in his role.

After Attorney General Jeff Sessions was fired last week, Whitaker assumed authority over the Russia investigation and the special counsel Robert Mueller and has been the subject of widespread reports and statements questioning his independence as an official.

Incoming House intelligence committee chairman Adam Schiff warned that any of acting Attorney General Matthew Whitaker's ulterior motives in overseeing the special counsel Robert Mueller's probe would be exposed if he did not recuse himself from the investigation.

Schiff told host Chuck Todd on NBC's "Meet the Press" that Democrats were prepared to challenge Whitaker's legitimacy in overseeing the Russia investigation and Mueller.

"I want to make this very clear, if he doesn't recuse himself, if he has any involvement whatsoever in this Russia probe we are going to find out whether he made commitments to the president about the probe," Schiff said. "Whether he is serving as a back channel to the president or his lawyers about the probe, whether he's doing anything to interfere with the probe."

He continued: "Mr. Whitaker needs to understand that he will be called to answer. Any role that he plays will be exposed to the public. We don't want there to be any ambiguity about that."

Since he was announced as Jeff Sessions' successor, Whitaker's independence has been widely questioned due to his past record and statements on the Justice Department's authority and the Mueller probe.

The Washington Post reported last week that Whitaker does not plan to recuse himself and would block Mueller from subpoenaing Trump if the president does not agree to a sit-down interview.

Read more: While he was Jeff Sessions' top aide, Matthew Whitaker reportedly advised Trump on how he could force the DOJ to cave to his demands

Department of Justice ethics officials will reportedly examine Whitaker's work and public record to determine any financial or personal conflicts that could interfere with his oversight of the Russia probe. The officials may then make a recommendation, but Whitaker would not be legally required to follow it.

Schiff's comments are the latest call from Democrats on Whitaker's legitimacy for the role and calls for him to recuse himself.

Incoming House Judiciary Chairman Jerrold Nadler said on ABC's "This Week" that Whitaker has shown "total hostility" to the investigation and his "appointment is simply part of an attack" on the special counsel.

Senate Minority Leader Chuck Schumer said on CNN's "State of the Union" that he, along with other top Democrats, sent a letter advising recusal to the Justice Department's chief ethics officer.

"Allowing a vocal opponent of the investigation to oversee it will severely undermine public confidence in the Justice Department’s work on this critically important matter," the letter said.

Watch Schiff's interview below: