President Donald Trump said Friday he was considering granting a posthumous pardon for Muhammad Ali — prompting a lawyer for his estate and family to say thanks, but no thanks: The boxing great had his criminal conviction overturned by the Supreme Court nearly 50 years ago.

Trump, who has issued several pardons and commutations in recent weeks, told reporters that he was "thinking about Muhammad Ali," for a pardon.

"He was not very popular then, his memory is very popular now," Trump said at the White House shortly before a departure for the G-7 summit in Quebec City, Canada. "I'm thinking about that very seriously."

Not long after, an attorney for Ali's estate and family responded, saying that a pardon wouldn't be necessary.

"We appreciate President Trump's sentiment, but a pardon is unnecessary. The U.S. Supreme Court overturned the conviction of Muhammad Ali in a unanimous decision in 1971," Ron Tweel, who has represented Ali and his family since 1986, told NBC News. "There is no conviction from which a pardon is needed."

But even though there is no Ali conviction on the books — the usual reason for a pardon — former DOJ pardon attorneys say it's too limited to think of a pardon as simply a conviction eraser.

"A pardon is an act of forgiveness," says former pardon attorney Samuel Morrison. "The pardon is for the conduct, regardless of whether there was or still is a conviction."

For example, In 1977, President Jimmy Carter granted amnesty, which is a pardon for a group, to all Vietnam-era draft evaders, many of whom had never been convicted.

Ali, who died in 2016, was convicted of draft evasion, sentenced to five years in prison and stripped of his heavyweight boxing title after he refused, in 1967, to report for induction to fight in the Vietnam War, declaring himself a conscientious objector and citing his Muslim faith.

Ali appealed his conviction, allowing him to remain out of prison, and the U.S. Supreme Court overturned the conviction in 1971 in a unanimous decision that found the Department of Justice had improperly told the draft board that Ali's stance wasn't motivated by religious belief.

Even as his health declined, Ali did not shy from politics — or from criticizing Trump. In December 2015, he released a statement slamming then-candidate Trump's proposal to ban Muslims from entering the United States. "We as Muslims have to stand up to those who use Islam to advance their own personal agenda," Ali said.

Meanwhile, Trump, who recently pardoned Jack Johnson, the first black heavyweight boxing champ, also said that he has a list of several thousand other names that he is reviewing for potential pardons.

Trump added that he was "looking at literally thousands of names."

Trump has issued several pardons and commutations so far in his presidency.

In addition to his posthumous pardon last month of Johnson, the African-American boxing legend who was convicted under a law that was used as a deterrent to interracial dating, Trump has also issued pardons to conservative provocateur Dinesh D'Souza, who pleaded guilty in 2014 to violating campaign finance laws; Joe Arpaio, a former Arizona sheriff who is a favorite of immigration hard-liners; I. Lewis "Scooter" Libby, the aide to former Vice President Dick Cheney who was convicted of obstructing justice and lying to authorities during an investigation into the outing of CIA operative Valerie Plame; and Kristian Mark Saucier, a Navy sailor who took photos of classified areas inside a nuclear submarine.

On Wednesday, Trump commuted the sentence of Alice Marie Johnson, who was serving life in prison on drug charges, after reality star Kim Kardashian West lobbied the president in an Oval Office meeting to intervene on her behalf.

Trump has also hinted at pardoning lifestyle and home merchandise mogul Martha Stewart, who was convicted in 2004 on charges related to insider stock trading, and former Illinois Gov. Rod Blagojevich, who was sentenced in 2011 to 14 years in federal prison on corruption charges, including attempting to solicit bribes in exchange for President Barack Obama's open Senate seat.