White House Press Secretary Sean Spicer said Monday there is “no need” for a special prosecutor to investigate alleged Russian involvement in the 2016 election or ties to the Trump campaign, pushing back on mounting Democratic calls for one in the wake of James Comey's firing.

“There is no need for a special prosecutor. There are two congressional committees and the FBI is conducting their own review,” Spicer said at Monday's press briefing.

Several Democrats since last week's abrupt firing have demanded that a special prosecutor be named to probe the Russia matter. Those calls have only mounted since Trump cited concerns about the Russia investigation in an NBC interview discussing his decision to remove Comey.

The demands, if not met, could lead to turbulence when Trump eventually names a nominee to replace Comey.

But Spicer said Monday there was "no collusion with respect to the president himself." Further, he said removing Comey was the "right thing" for the FBI and the country, even though Trump knew the move could "lengthen" the Russia probe. He questioned why more resources should be brought into that investigation.

“You have a House committee, a Senate committee, an FBI review—I don’t know why you need additional resources when you already have three entities,” Spicer said.

Spicer also said the process of finding a replacement is running “completely as it should,” and being headed by Attorney General Jeff Sessions and Deputy Attorney General Rod Rosenstein -- whose memo on Comey's handling of the Hillary Clinton email case was cited by the White House as rationale for his firing.

Senate Majority Leader Mitch McConnell, R-K.Y., signaled last week that he had no intention of calling for a special prosecutor, but did invite Rosenstein to brief the full Senate regarding the removal of Comey.

Rosenstein accepted, and the briefing is set for Thursday.

Senate Minority Leader Chuck Schumer, D-N.Y., said he was "pleased" to hear from Rosenstein, but doubled down on his call for a special prosecutor to take charge of the Russian investigation.

“I hope that senators from both sides of the aisle will use this opportunity to seek the full truth regarding Director Comey’s firing, to press the Deputy Attorney General to make way for a special prosecutor, and to ensure the administration will preserve and make public any audio recordings of conversations between the President and the former director,” Schumer said in a statement on Monday.

House Minority Leader Nancy Pelosi, D-Calif., wrote a letter on Monday to House Speaker Paul Ryan, R-Wis., calling on him to invite Rosenstein to brief the House as well on the matter, and reiterating the need for a special prosecutor.

“In the absence of an independent counsel statute, there is support for a special prosecutor appointed by the Justice Department,” Pelosi said in a statement. “It is important that the prosecutor be chosen by the highest-ranking Justice Department official who has not been appointed by President Trump.”