WASHINGTON — Congressional Democrats say that a classified briefing held Thursday for top leaders about the FBI's investigation into President Trump's 2016 campaign did not offer evidence that supports the allegation that an intelligence agency placed a spy in the campaign.

"Nothing we heard today has changed our view that there is no evidence to support any allegation that the FBI or any intel agency placed a spy in the Trump campaign," said a statement Rep. Adam Schiff, D-Calif., read to reporters on behalf of himself, House Minority Leader Nancy Pelosi, D-Calif., Senate Minority Leader Chuck Schumer, D-N.Y. and Sen. Mark Warner, D-Va.

Schiff, the top Democrat on the House Intelligence Committee, attended a noon briefing at the Justice Department originally planned as a private briefing for leading House Republicans on classified information they have been seeking about the FBI's investigation into Trump's presidential campaign. Pelosi had received the invitation to attend, but sent Schiff instead, she told reporters at the Capitol on Thursday.

Trump's lawyer, Emmet Flood, was among the group attending the DOJ briefing, a Justice Department official said. Flood was later seen walking in with White House Chief of Staff John Kelly to a similar classified briefing for top congressional leaders, known as the "Gang of Eight," on Capitol Hill Thursday afternoon.

In a statement after the Capitol Hill meeting ended, the White House said that Kelly and Flood left before the meetings officially began.

"Neither Chief Kelly nor Mr. Flood actually attended the meetings but did make brief remarks before the meetings started to relay the President’s desire for as much openness as possible under the law," the statement said. "They also conveyed the President’s understanding of the need to protect human intelligence services and the importance of communication between the branches of government."

Warner spoke briefly to reporters after the meeting, confirming the White House statement about the officials leaving before the briefing began, but criticizing their decision to attend at all. "There’s never been a Gang of Eight meeting with that kind of White House presence,” he said.

In a move Democrats have said could harm national security, House Intelligence Committee Chairman Devin Nunes, R-Calif., has been trying to shake loose information about a confidential FBI source. Originally, the briefing was arranged for Nunes; Rep. Trey Gowdy, R-S.C., the chairman of the House Oversight and Government Reform Committee; and Speaker Paul Ryan, R-Wis.

The White House announced this week that, after a meeting with Trump, top officials at the Justice Department and FBI had agreed to sit down with the lawmakers to discuss the material in question. Trump has been referring to the FBI's use of an informant as "spygate" in what critics contend is an effort to discredit the initial investigation into the president's campaign and undermine special counsel Robert Mueller's ongoing probe.

The lawmakers heard from Deputy Attorney General Rod Rosenstein, FBI Director Christopher Wray and Director of National Intelligence Dan Coats, with White House chief of staff John Kelly also attending. Democrats, including Schumer, had said Kelly should not be present for the briefing because of his proximity to the president, whose campaign is under investigation.

After Democrats objected to the break in protocol — in almost all cases, classified information that an administration shares with members of Congress is given to top leaders in both parties — a second briefing was also scheduled for 2 p.m. ET Thursday on Capitol Hill.

"There shouldn't be a pre-meeting with two GOP members who effectively acted as Donald Trump's legal defense team in Congress," Schiff said on MSNBC's "Morning Joe" Thursday.

The second meeting was for the so-called Gang of 8 — the top Republican and Democrat in the party leadership in each chamber and on the intelligence committees in each chamber.

Earlier this week, Nunes and Gowdy had requested a review of the classified materials and White House and DOJ officials agreed that they'd provide a briefing to Republicans. Over the last 36 hours, however, Kelly was in close contact with Senate Majority Leader Mitch McConnell, R-Ky., to renegotiate the contours of the meeting and both agreed it would make sense to widen who could be involved in the briefings.

The White House acknowledged that Thursday's document review would likely not be definitive concerning the president's claims that his campaign was spied on in 2016 for political reasons. A senior administration official “doubt[ed] anything shown today conclusively proves either way” what the president has been suggesting."

Nunes recused himself from the House panel's Russia probe last year after saying a confidential source had given him information suggesting the Trump campaign was monitored by U.S. law enforcement. Nunes received the information on White House grounds, leading to allegations that he was coordinating with the White House while he was investigating the Trump campaign's ties to Russia.

The House committee investigation wrapped up last month.