Analysts believe Trump's newfound enthusiasm for exercising pardoning power is because it's a presidential privilege unchecked by other branches of government, which can not be said of most of Trump's other policies.
FILE - Muhammad Ali, left, assumes his former fighting stance while joking around with Vietnamese people on the path outside of Ho Chi Minh's former home in Hanoi, Vietnam, May 11, 1994.
Trump's musing about an Ali pardon was blasted by the Rev. Al Sharpton, who accused the president of "nothing more than grandstanding". Actor Sylvester Stallone alerted him to that case.
"We have 3,000 names".
"The power to pardon is a attractive thing", he added.
Ali, born Cassius Marcellus Clay Jr., is one of the most celebrated athletes in U.S. history.
In an unsigned opinion, the court said that the Justice Department had misled Selective Service authorities by advising them that Ali's claim as a conscientious objector was neither honest nor based on religious tenets.
Though Ali was convicted of evading the draft for the Vietnam War in 1967, the Supreme Court later overturned that decision in 1971. And now he's considering another legendary boxer for a pardon: Muhammad Ali, who died in 2016 of Parkinson's disease. "And he wasn't very popular then", Mr Trump said.
Trump described Ali as "not very popular" at the time of his refusal to serve in the military during the Vietnam War.
Updated with reaction from Ali's former lawyer at 10:02 a.m.
The White House did not immediately respond to questions about why the president feels one is warranted.
Pardons have been at the front of President Donald Trump's mind lately.
"This was quite a surprise to everybody this morning when we heard about it", he said Friday during a phone interview.
The president has been operating outside the usual Justice Department clemency protocol, in which submitted cases are carefully considered based on their merits, and recommendations made. Kim Kardashian visited the White House last week to ask Trump to consider pardoning Johnson.
Trump insisted Friday that he was also interested in clemency for regular people and those without high-profile backers.
"I think the pardon should go to those who kneel, that's who should get the pardons, that would be putting it in the right perspective, in the right place", she explained. "So this, to our knowledge, came out of the blue, for reasons that I'll let you speculate".