(NewsNation) — A biographer who spent two years embedded in the Biden White House calls it the “most scripted” in modern history and said he was not allowed to interview the president in person, only in written form.

Chris Whipple spent two years speaking with aides and allies of President Joe Biden for his book “The Fight of His Life: Inside Joe Biden’s White House.” Whipple told NewsNation that controlling the narrative is the DNA of the White House.

“This is a batten-down, buttoned-up White House that has been from day one,” Whipple said.

The controlled appearances and use of teleprompters have been under scrutiny lately as Democrats fear Biden won’t be able to win in November or serve another four years. Following a poor debate performance, a number of Democrats are now calling on the president to step down from the ticket.

Biden has resisted, saying he has no intention of leaving and there is nothing that would convince him to give up.

In return, skeptics in his own party have suggested an inner circle that has shielded the president and carefully managed his public appearances has concealed Biden’s mental state from the public and his allies.

Whipple said his agreement with Biden and his staff reflected the planned and controlled nature of the administration.

“When it came to interviewing the president himself, the arrangement was written questions and written answers,” Whipple said of his experience. “Perhaps they were trying to protect the president from some unguarded comments or this is just the way this White House operates.”

That is a significant departure from the Trump White House, where off-the-cuff comments from the president frequently led to scrambling from staff as they tried to keep up.

Whipple said he’s starting to see signs that things in Biden’s camp are changing, as supporters like Nancy Pelosi have signaled that they are open to replacing him, even if they have stopped short of calling on him to drop out.

Embedded in the White House for the first two years of the administration, Whipple said he has noticed a change in Biden.

“I think the president’s mental state has deteriorated more recently,” Whipple said.

Whipple said he didn’t witness any private moments that would have led him to question the president’s mental capacity, but noted that in public, the president has made stumbles in the past. As Biden focuses on a NATO summit in Washington, D.C., Whipple said it’s a key moment for the campaign.

“I think today is absolutely critical,” he said. “The press conference he does after the NATO meetings, its going to be critical and obviously there will be no net. He’s got to do this on his own.”