President Donald Trump has learned about his power to issue pardons. And in the last week, White House aides have suggested that he use his first one on a controversial choice: Sheriff Joe Arpaio, the schismatic Arizona lawman convicted of contempt of court.

In recent days, speculation has mounted that Trump will follow through on this suggestion at a campaign rally in Phoenix on Tuesday. Should he do so, it will be a unique moment in modern presidential politics. Trump will have given the first pardon of his presidency to someone for what appears to be purely political reasons and he will have done so without going through the normal review process.

The possibility has left some clemency advocates feeling a little queasy.

“There are literally hundreds of no-name people we’ve never heard of, who will never been in the newspaper, who are not cause célèbres, who have had applications waiting and waiting and waiting,” said P.S. Ruckman, political science professor at Northern Illinois University. “They’re sick to their stomach right now reading about Arpaio getting a potential pardon, that’s breaking their heart.”

Like George W. Bush and Barack Obama before him, Trump has proven stingy with the pardon power granted to the president. And that’s probably a generous way to put it. Two hundred days into his presidency, he has yet to pardon anyone. This isn’t unprecedented. It took Obama more than 600 days to issue a pardon. He nearly broke the record for fewest pardons, though he granted more clemencies than any other president by shortening the sentences of more than a thousand people.

Over the last two administrations, there’s been a dramatic drop in the number of pardons meted out, even as the federal prison population has exploded. Obama pardoned 212 people. George W. Bush pardoned only 189. Bill Clinton and Ronald Reagan, meanwhile, pardoned 396 and 393 people respectively, according to the Justice Department.

Ruckman said that most American presidents started pardoning people in their first month in office, and kept pardoning at a regular clip through their administrations. The drop-off in pardons is a relatively new change. And while high-profile grants of clemency to political allies get the most press—think Bush’s commutation of Scooter Libby’s sentence or Bill Clinton’s pardon of Democratic mega-donor Marc Rich—the vast majority of people who get pardoned never become household names.

Instead, they have to serve time in prison, wait five years, and then apply for clemency. And then, after they apply, they often have to wait years for the Justice Department’s Office of the Pardon Attorney to review their request, sign off on it, and send it to the White House for final approval—if they get that far. The pardon attorney’s office has a backlog of thousands of cases.

Arpaio isn’t part of that backlog since he hasn’t applied for a pardon yet, according to a person with knowledge of the pardon process. He would need one eventually because a federal judge found him guilty of criminal contempt—a misdemeanor—for detaining immigrants solely because they are undocumented, in violation of a court order.

Were Trump to give his first pardon to Arpaio, who endorsed him during the Republican presidential primary, Ruckman argues that it would undercut the populist message from the campaign.

“It would give people the sense that only famous people, cause célèbres, and connected people are going to get pardons from Trump,” Ruckman said.

Sam Morison, an attorney who worked in the Justice Department’s pardon office for more than a decade, predicted Trump will pardon Arpaio when he goes to Arizona, though he added that it would send a terrible message.

“He hasn’t even been sentenced yet, he’s just been convicted,” Morison said. “And he’s not contrite, he doesn’t accept responsibility—quite the opposite. So in that sense, it’s very unusual. And the only reason he’s getting any traction at all is that he’s a well-known political figure. So it is special pleading of the worst kind.”

That said, there could be an upside for people who want a more merciful criminal justice system: Many advocates argue the Justice Department shouldn’t have anything to do with pardons—that the department is institutionally biased in favor of prosecutors and lengthy sentences, and averse to self-correction.

Margaret Love, who headed the Office of the Pardon Attorney for seven years, wrote a law review article making this case in 2015.

“[H]ow could the agency responsible for convicting people and putting them in prison also be tasked with forgiving them and setting them free?” she wrote.

It’s a question that bedevils many former Justice Department officials. And, quietly, they hope Trump might take enough of a shine to the pardoning power that he moves the whole process to the White House.

One former Justice Department official put it simply:

“People would be so grateful that he’s rescued this important Constitutional power from the clutches of the DOJ.”

Correction: An earlier version of this story incorrectly stated that the pardon attorney is a presidentially-appointed position. It is not.