Jon Meacham on MSNBC's "Morning Joe." MSNBC Presidential historian Jon Meacham said Tuesday that President Donald Trump told him last year that he could have negotiated a deal to avert the Civil War.

On Monday, Trump asked a Sirius XM radio host why the Civil War "could not have been worked out," and claimed that President Andrew Jackson was outraged by the war and would have avoided it, despite the fact that Jackson died 16 years before the war began.

Speaking to MSNBC's "Morning Joe," the famous historian dismissed Trump's argument as a "projection of the president's fundamental and enveloping narcissism," and recalled an interview with Trump last year during which the then-Republican presidential candidate mentioned the Civil War.

"He told me a year and a half ago that he could've done a deal to avert the war," Meacham said.

He added: "The presidency itself enhances your fundamental characteristics. It's very hard once you're there to change. Some people do, and that's why we call them as great presidents. But most people once they enter the Oval Office just become more like themselves."

Meacham is frequently cited as a preeminent Jacksonian expert.

In recent months, Meacham has cautioned Trump against fully embracing the Jacksonian presidential model, noting Jackson's brutality towards minorities and unapologetic slave ownership.

Watch the clip via NBC: