Democrats are running a smear campaign against House Intelligence Committee Chairman Devin Nunes (R-CA), after he revealed last week that members of Trump’s transition team were caught up in “incidental surveillance” targeting foreigners.

Nunes’ revelation appeared to bolster President Trump’s assertion that the former Obama administration had spied on the incoming president.

But now Democrats are calling for Nunes to recuse himself from investigating what role Russia played in the 2016 presidential elections, and who illegally leaked to media conversations between Trump’s former National Security Adviser Michael Flynn and the Russian ambassador to the U.S.

House Minority Leader Nancy Pelosi (D-CA) called for Nunes to recuse himself from the investigation, and Senate Minority Leader Chuck Schumer (D-NY) demanded that Nunes be removed from the intelligence committee altogether.

“Unfortunately, the House Intelligence Committee has come under a cloud of suspicion and partisanship,” Schumer said.

The smear campaign continued Tuesday. The Washington Post said Nunes “abruptly canceled” a committee hearing with former acting attorney general Sally Yates, and suggested it was because the White House did not want her to testify.

But a congressional aide said that Nunes had announced the hearing was merely postponed — not canceled.

The aide said the hearing was postponed in order to hold a closed hearing with FBI Director James Comey and NSA Director Adm. Michael Rogers first, since so much of their testimony last week could not be discussed during an open hearing.

The aide also said it was postponed before Nunes was made aware the Department of Justice considered part of her testimony to be barred from discussion in a hearing due to presidential communication privilege, and referred the matter to the White House. The White House later said it never objected.

“He’s being vociferously attacked right now by the Democrats because they want to try to undermine his authority in order to further their argument that we need to have a special commission to take charge of the Russia investigation, because they feel like they’ll have more control in that venue than they do being the minority on a congressional committee,” the aide said.

Nunes has said he is staying put. So far, only one House Republican has supported a Democratic bill to create an independent commission — Rep. Walter Jones (R-NC), according to The Hill.

The Democrats’ campaign to get him removed began last week, after Nunes announced he saw evidence that the communications of members of President’s Trump’s transition team were listened in on, and their identities “unmasked” despite protections meant to protect U.S. citizens, and disseminated among U.S. intelligence agencies.

Unmasking refers to identifying Americans incidentally caught up in surveillance of foreigners, which requires senior official approval and if the identity of that person is relevant to national security or a criminal investigation.

Nunes briefed reporters and the White House on what he found before he shared it with other members of the committee, angering Democrats who accused him of trying to provide cover for the president.

Democrats have also seized on a visit Nunes made the day before his announcement to a facility on the White House grounds, to suggest he was doing something inappropriate.

But Nunes explained Monday on CNN’s “Wolf Blitzer” that he went to a Sensitive Compartmented Information Facility (SCIF) within the Eisenhower Executive Office Building, next to the West Wing, in order to view intelligence widely distributed throughout the executive branch, but unavailable to members of Congress.

“The Congress has not been given this information, these documents. And that’s the problem,” he told Blitzer. “It was distributed widely through the executive branch.”

He said the reason it was unavailable to members of Congress was because it had nothing to do with the Russia investigation that members were conducting, but was related to his previous efforts to know whether the identities of Americans were being properly masked in intelligence reports.

“So, I had been working this for a long time with many different sources and needed a place that I could actually finally go, because I knew what I was looking for and I could actually get access to what I needed to see,” he said.

“This had nothing to do with Russia, nothing to do with the Russian investigation, there was no way for the folks that I had been working with to actually, to bring this forward to light. There was no way I could view that, because they couldn’t get it to the House Intelligence Committee,” he said of his sources.

Nunes scoffed at reports that characterized him sneaking off to the SCIF the night before.

“The sun was out. And I actually stopped and talked to several people along the way. Many foreign dignitaries were there. Some I recognized, I said hello, had conversations with them,” he said.

He also said he was “quite sure” that no one next door at the West Wing even knew he was there, and that he was not planning to share what he learned with the White House.

However, he said he briefed the president the next day because what he saw had nothing to do with Russia, but with individuals’ names being included into intelligence reports.

“I was very concerned and I thought the President of the United States should know,” he said. “And that’s why I went and told him.”

Nunes said the intelligence he saw showed unmasking of individuals between November through January. He said so far, only Flynn’s name was illegally leaked to media, but he’s not sure yet about others.

Nunes said from what he saw, the unmasking appeared unnecessary.

“As somebody who supports our national security apparatus, it bothered me that this level of information would be included in intelligence reports, because it just wasn’t necessary, from my point of view, legal or not,” he said.

As some reports have mentioned, it would have been normal for Trump transition aides to speak with foreign governments. According to a March 23 Reuters report:

A U.S. government source said it was logical, if not normal, that communications from Trump aides would have been incidentally intercepted by U.S. agencies after his election, given that they would have an interest in talking to foreign governments. Trump took office on Jan. 20.

Decorated former Central Intelligence Agency career officer Gary Berntsen told Breitbart News in an interview that he is sympathetic to Nunes having to visit an executive branch facility to view specific intelligence.

He said contrary to popular belief, members of the intelligence committees don’t have access to whatever intelligence they want, and that it makes sense that Nunes had to view it at an executive agency SCIF.

“They don’t have full access,” he said. “They have more access than other members, but their view is limited.”

He explained that members of Congress typically get “finished intelligence,” not raw data or operational traffic.

“I am a little bit sympathetic,” he said. “He’s trying to do his best to figure it out.”

On March 15, Nunes and Schiff requested the FBI, CIA, and NSA to submit the number of times Americans’ identities have been unmasked, and what procedures are used to determine when to unmask and disseminate those identities.

A deadline of March 17 has passed, and only NSA has provided some information, but the committee is still waiting for answers.

“What I’m raising here is vital to national security. We cannot allow Americans’ names to be either masked improperly or unmasked improperly. And we have a duty and a responsibility to get to the bottom, to see if this was done properly or not,” he said.