President Donald Trump lied his way onto the Forbes list of richest Americans and used a fake persona to do so, according to a former writer for the magazine.

In a piece for The Washington Post, Jonathan Greenberg recounts the difficult task of tallying up the future commander-in-chief's wealth as he built his New York-area real estate empire.

Trump's persistence in trying to convince journalists how rich he is has been well documented over the years, but Greenberg's piece takes it a step further. He asserts that Trump used a fake voice and pseudonym of "John Barron" to convince the magazine that he should be on the Forbes 400 list.

Greenberg said "Barron" called him in May 1984 to persuade him to push up his estimate of Trump's wealth. The caller had a thicker New York accent and some different "cadences," but Greenberg is certain he was speaking to the future president. The calls were off the record, but Greenberg believes exposing them now is important.

In addition to Trump, several of his confidants also called the magazine to convince it that he belonged on the list.

"This was a model Trump would use for the rest of his career, telling a lie so cosmic that people believed that some kernel of it had to be real. The tactic landed him a place on the Forbes list he hadn't earned — and led to future accolades, press coverage and deals. It eventually paved a path toward the presidency," Greenberg wrote.

Trump's name appeared on the Forbes 400 list off and on for several years and has been on it since 1996. During the campaign, he claimed to have a personal fortune of $10 billion, but Forbes most recently listed his wealth at $3.1 billion.

CNBC has reached out to the White House for comment. Greenberg noted that neither the White House nor the Trump Organization responded to his requests for comment. Forbes did not immediately return an email for comment.

Read Greenberg's full piece in the Post here.