Trump will quickly 'unspool inside himself' without the 'constant feed of attention' he got as president: Biographer
President Trump. (AFP)

Donald Trump is starting a new life as a former president, and one of his biographers thinks he'll quickly unravel out of the spotlight.

The outgoing 45th president faces a slew of criminal investigations of his family's business empire and possibly some of his actions in the White House, but former biographer Tim O'Brien told Politico Magazine that he'll fall into a downward spiral without the constant attention he got in office.

"Apart from whatever happens to him criminally, I also think the other penalty for him is just being ignored," said O'Brien, who wrote Trump Nation. "Because he's gone through these different parts of his life where he's been out on the tundra, cold and ignored and lonely. He's lonely all the time. I think he's a very lonely person generally."

Trump faced life outside the spotlight in the 1990s, when he was a punchline to jokes about the 1980s and an occasional guest on Howard Stern's radio show, but "The Apprentice" propelled him back into the national conversation and paved the way for his presidential run, O'Brien said.

"Now for him to wind up sitting down at Mar-a-Lago, playing golf and kvetching and screaming at television screens, and occasionally venturing out to do road shows and support some candidates — I think without this constant feed of attention and interest he's going to unspool inside himself because he needs it so much," O'Brien said. "and I think that's another possible penalty that could emerge."

Trump won't entirely fade away, thanks to the likely criminal investigations and his status as an ex-president, but O'Brien doesn't think that will be enough to sustain his addiction to attention for long.

"That's the kind of attention he doesn't care about," he said. "I don't think he cares about history books, really, or the legacy of his office. I mean, he may a little bit, but what he really cares about is what's right in front of him right now, not how he's remembered after he's dead."

"He's a bottomless pit of need," O'Brien added, "and he needs to replenish it every single day and would love it if he could just be in front of a geyser of attention if he could, and I think thimblefuls of attention won't be enough for him."