White House national security adviser Robert C. O’Brien said former vice president Joe Biden appears to have won the 2020 presidential election and pledged to oversee a “very professional transition” on the National Security Council to the new administration once he is determined to be the winner.

O’Brien’s comments came with a caveat but appeared to mark one of the first public admissions of defeat from President Trump’s inner circle. Other top aides, including Secretary of State Mike Pompeo, have publicly suggested Trump will secure a second term, even though Biden is on track to win 306 electoral college votes, compared with Trump’s 232. There is no evidence of voter fraud that would affect the result, despite the president’s attempts to cast doubt on the validity of the Nov. 3 vote.

“If the Biden-Harris ticket is determined to be the winner, and obviously things look that way now, we’ll have a very professional transition from the National Security Council. There’s no question about it,” O’Brien said at the Global Security Forum, an annual forum that usually takes place in Qatar but was held virtually because of the coronavirus pandemic.

The Post's Ashley Parker explains why some Republicans followed President Trump's lead in denying the reality of the election and the danger they're posing. (The Washington Post)

O’Brien said the Biden team was planning to bring in “very professional folks” to take positions on the National Security Council, many of whom understand the job and have worked in previous administrations.

The national security adviser’s pledge comes amid concerns that the Trump administration’s refusal to trigger the formal transition process could jeopardize national security by giving the incoming team fewer resources to prepare.

The administrator of the General Services Administration, a federal agency that handles leases for government facilities and other administrative tasks, is supposed to issue the determination after an apparent winner emerges. Emily Murphy, the Trump-appointed administrator, has refused to do so.

O’Brien also addressed Trump’s recent firing of his defense secretary, Mark T. Esper, who was replaced in an acting capacity by Christopher C. Miller, a former Green Beret who served on O’Brien’s staff as senior director for counterterrorism and transnational threats. As O’Brien began promoting his vision for the future of the U.S. Navy earlier this year, some in the defense world saw him as gunning for Esper’s job in a second term or seeking to take over his portfolio.

“There was a lot written about Mark Esper and myself. I never wanted Mark Esper’s job,” O’Brien said. “I just wanted to see Mark Esper succeed and do a great job as secretary of defense.”

Esper, who fell out with Trump over his refusal to back the use of active-duty U.S. troops to quell protests in the nation’s capital earlier this year, didn’t immediately respond to a request for comment.

O’Brien said that he didn’t think he and Esper had any disagreements and suggested that the news media overplayed any divides.

A series of personnel moves at the Defense Department in recent days have brought top former National Security Council officials in to run the agency. In addition to Miller, former National Security Council officials Kash Patel and Ezra Cohen-Watnick have taken on roles as chief of staff and acting undersecretary of defense for intelligence, respectively.

O’Brien previously served as the Trump administration’s top envoy for negotiating the release of American hostages and detainees abroad. On Monday, he said he hoped the Trump administration would be able to free more Americans before the end of the president’s term.

He said the administration was continuing to use all its available resources to bring home Austin Tice, an American journalist who was taken captive in Syria in 2012. Tice’s articles were published by The Washington Post, McClatchy newspapers and other news organizations.