On Tuesday, in his last week in office, President Obama commuted the sentence of one of the most controversial figures of his presidency: with the wave of a pen, he shrunk former Army private Chelsea Manning's 35-year sentence for giving troves of diplomatic documents to WikiLeaks. Obama also pardoned retired Gen. James Cartwright, who pleaded guilty in October to lying in a leak investigation.

But politicians behind bars wishing that Obama is suddenly in a forgiving mood should not hold out hope.

Commutations — a shortening of a sentence but not a full pardon of the crime — are rare things for presidents to grant. It's even rarer for presidents to grant them to fellow politicians — and even rarer to get one from Obama. Obama, who in his first term was famously stingy with granting all forms of clemency, has never commuted the sentence of a politician.

In fact, 91 percent of Obama's clemency grants have been commutations of sentences, as Northern Illinois University Professor P.S. Ruckman Jr. recently calculated on his Pardon Power blog. And most of those were of low-level drug offenders, the White House said.

“Whatever one wants to say about Obama, he has played it straight,” Ruckman said. “President Obama has been wildly stingy with pardons, and his clemency record, overall, has featured no stunts.”

That's bad news for at least two politicians sentenced during the Obama era, who are serving some of the longest prison sentences ever handed down to politicians and who are asking Obama for mercy.

Former Illinois governor Rod Blagojevich (D) is asking Obama to do away with the rest of his 14-year sentence for trying to sell the U.S. Senate seat vacated by Obama. And former congressman Chaka Fattah (D-Pa.), who is facing a 10-year prison sentence for corruption charges, is asking Obama not only to get him out of prison but also to pardon his crimes. (Edward Snowden — a political figure, though not a politician, who has not been tried or convicted of anything — has also asked Obama for clemency.)

Throughout history, presidents have shied away from these kinds of high-profile requests; that's understandable, because of the optics they create. Handing a fellow politician or a public figure a get-out-of-jail-free card on your way out the door can smell fishy, especially for a president like Obama, who has shied away from granting clemency almost entirely to low-level drug offenders.

“If you're stingy with pardons and then you go and pardon your friends and cronies, that looks egregious,” Ruckman said.

The most high-profile exception to the rule, of course, is former president Richard M. Nixon, who was pardoned by his successor, Gerald Ford, for his involvement in the Watergate scandal. But Ford was careful to frame his decision to pardon Nixon as less about Nixon and more about avoiding a drawn-out trial related to an event people just wanted to be over.

We were curious which politicos besides Nixon had received pardons, so, at The Fix's request, Ruckman compiled a list of notable political pardons and commutations. He figures that about 50 politicians or major political figures have been pardoned by presidents in the country's history.

“There's this perception sometimes that people get pardons for people who are connected,” Ruckman said. “But, he said, it's a “small” list.

The Fix's Philip Bump helped us visualize some of the lucky few politicians who have received pardons or commutations from presidents. Below, I share some of their stories.

Augustus Hill Garland, pardoned by Abraham Lincoln

Sometimes pardons can give people second chances at political careers. Garland, the first guy on our list, was a Confederate politician. Lincoln pardoned him after the Civil War ended, and he went on to be attorney general under Grover Cleveland.

Francis Shoemaker, pardoned by FDR

And sometimes clemency really is specifically granted to give someone a second political life. In 1933, Francis Shoemaker was elected to Congress from Minnesota with a criminal record. There was a big debate in the House of Representatives whether that prevented him from being seated. President Franklin D. Roosevelt ended that debate by abruptly pardoning Shoemaker.

Marvin Mandel, sentence commuted by Ronald Reagan

Mandel is one of the first modern-day politicians to have a president help him get out of jail.

Mandel (D) was convicted in 1977, a decade into his term as governor of Maryland, of mail fraud and racketeering related to accepting bribes and vetoing legislation that would help make his allies money on a racetrack deal.

In 1981, President Ronald Reagan cut his prison sentence short by five months. The attorney general said the Justice Department recommended commuting his sentence because Mandel would have served four months more than any of the other defendants in the case.

Mandel told reporters his release left him “speechless.” “I'm going home,” he said. His wife told reporters that Mandel burst into tears when he heard the news: “He cried, I can't tell you how he cried.”

Melvin Reynolds, sentence commuted by Bill Clinton

Reynolds, a Democratic member of Congress from Illinois, was already serving five years in prison in the ’90s related to having sex with a campaign volunteer when his prison time was extended to more than 10 years after he was convicted of bank fraud.

Reynolds was halfway through his second sentence when Clinton, in his last two hours in office in 2001, commuted the rest of Reynolds's sentence for bank fraud (along with last-minute pardons or commutations of about 175 other people).

“You will never convince me that God didn’t arrange that,” a shocked Reynolds told a Baptist congregation shortly after being released.

(Chicago Magazine's Carol Felsenthal said it was actually the Rev. Jesse Jackson — and several other powerful Illinois politicians — who arranged it.)

Reynolds's story is also a warning for presidents about how risky commutations can be. In 2014, Reynolds was arrested in Zimbabwe for having pornography, which is a crime there. He is also facing charges in the United States for failure to file federal income-tax returns, but he hasn't showed up for trial, saying he fears for his life.

Dan Rostenkowski, pardoned by Bill Clinton

Pardons can happen after someone is out of jail, too. In 2000, Clinton pardoned one of the most powerful members of Congress to have gone to jail — the late Chicago-area Democratic congressman Dan Rostenkowski. He was the head of the House Ways and Means Committee and the poster politician for old-school, smoke-filled wheeling and dealing.

Rostenkowski had lost reelection in 1994 after he was indicted on charges related to misusing hundreds of thousands of dollars of taxpayer money. He served a little more than a year in prison and was three years out of prison when Clinton pardoned him in 2000, wiping his crimes clean.

The pardon was a surprise for most people watching Clinton's blitz of last-minute pardons.

Then again, history suggests any presidential pardon for a politico should come as a surprise, anyway.