Democratic Rep. Elijah Cummings of Maryland says he will do "anything and everything" in his power to ensure the findings of special counsel Robert Mueller's Russia probe are released to the public. Cummings is set to become chairman of the House Oversight and Government Reform Committee when Democrats take control of the lower chamber in January.

"I would do anything and everything in my power to have the findings presented to not only to the Congress, but to the people of the United States," Cummings said on "Face the Nation" Sunday. "I think it's very important."

Cummings would wield subpoena power as chairman of the Oversight Committee, and could try to force Mueller's findings to be made public if the Justice Department decides not to release them.

Cummings also said "it's not clear" whether Matthew Whitaker's appointment as acting attorney general was lawful. He said he wants to "look at every angle" to see if Democrats can force Whitaker to recuse himself from the Russia probe, which now falls under his purview.

"I don't know that we have that power, but we're going to certainly look at every angle," Cummings said. "I question whether or not it was actually a legitimate appointment, since he's not been confirmed by the Senate."

Cummings said his other top priorities as chairman are voting rights, protecting pre-existing conditions, the 2020 census and the postal system.

He also endorsed Nancy Pelosi for speaker of the House, brushing off a suggestion that House Democrats need more African-American members in the party's leadership.

"All of us are leaders," he said. "We could only have one speaker at a time. Nancy Pelosi has simply been phenomenal."