Former House Speaker Newt Gingrich compared Donald Trump to former President Andrew Jackson when asked about how mentally fit the Republican presidential nominee is for office.

"Yeah, and my answer would be sure," Gingrich told Michael Barbaro in a podcast interview with The New York Times.

"Sure?" Barbaro asked him on the election podcast "The Run-Up" released Tuesday.

"Sure. I mean, he is at least as reliable as Andrew Jackson, who was one of the most decisive presidents in American history," Gingrich explained. "Nobody would have predicted Abraham Lincoln's capabilities before he became president, and most people didn't believe him while he was president."

When asked to elaborate, Gingrich said Trump has the "willingness to break up a system which is decaying."

"I think the kind of personality that is prepared to be outside the total establishment and have the self-confidence to take on the establishment of both parties is a personality which will by definition not be normal," Gingrich added.

Gingrich endorsed Trump in mid-May, saying he would "work very hard for the nominee."

Jackson, the United States' seventh president, was a colonel in the Tennessee militia, owned hundreds of slaves who worked on the Hermitage Plantation and killed a man in a duel over Jackson's wife Rachel. Jackson also won a decisive battle in the War of 1812 over the the British invading army at the Battle of New Orleans.