As Obama prepares to leave office in two weeks he has the chance to pardon controversial figures, including Edward Snowden, Chelsea Manning and Taliban captive Bowe Bergdahl.

Thousands of names have been submitted to the 44th president for clemency before he hands over the White House to Donald Trump on January 20.

Obama is fielding pressure from all sides to grant unlikely pardons or commutations of sentences to people whose supporters say have been unjustly sentenced or sought out by the justice system.

Thousands of names have been submitted to President Barack Obama for clemency before he leaves office in two weeks

While some seeking a pardon are minor drug traffickers, others are much more high-profile and whose pardons would draw international attention..

Among them is Bowe Bergdahl, a US Army sergeant held captive for five years by the Taliban before his release in a prisoner swap, who is due to be court-martialed for desertion.

Leonard Peltier, a Native American activist convicted for the 1975 deaths of two FBI agents in what his supporters say was a setup, is also hoping to enjoy Obama's good graces.

Then there's Edward Snowden, who made the shattering revelation in 2013 of a global communications and internet surveillance system set up by the United States.

Among those hoping for an unlikely pardon or commutations of sentences are Bowe Bergdahl (left) and Edward Snowden (right). Bergdahl was held captive by the Taliban and is now facing court-martial for desertion

The 33-year-old, a refugee in Russia, is backed by numerous celebrities like actress Susan Sarandon and singer Peter Gabriel, as well as Amnesty International and the American Civil Liberties Union.

If Obama fails to pardon Snowden, his supporters say he may face the death penalty under the incoming administration of Republican Donald Trump, who has called him a "terrible traitor."

In another leak case, Chelsea Manning is serving a 35-year sentence in solitary confinement for handing 700,000 sensitive military and diplomatic documents to WikiLeaks, some of them classified.

Activists say her sentence is excessive and point to the psychological frailty of the transgender soldier who has already made two suicide attempts.

Even though the White House has dismissed a possible pardon for Snowden and Manning, their supporters are still hoping for a final magnanimous gesture from a president about to leave the constraints of his high office on January 20.

But both cases present unique challenges: Snowden has yet to be sentenced and merely faces espionage charges in the US, while Manning has an appeal pending before military court.

Chelsea Manning, an army intelligence analyst who went by Bradley before she was imprisoned, has asked for leniency, too. Manning is serving a 35-year-sentence for giving classified information to Wikileaks

The US Constitution allows a president to pardon "offenses against the United States" and commute -- either shorten or end -- federal sentences.

Some US presidents have used this regal power of leniency in a pointed way near the end of their term in office.

On the last day of his term in 2001, Democratic president Bill Clinton granted pardon in a highly controversial move to late fugitive trader Marc Rich, whose ex-wife had been a major donor to Democrats.

Obama has so far granted 148 pardons since taking office in 2009 -- fewer than his predecessors, who also served two terms, George W. Bush (189) and Bill Clinton (396).

But he has surpassed any other president in the number of commutations, 1,176.

So far Obama has granted 148 pardons and 1,176 commutations since taking office in 2009

Most of those who benefited from the president's clemency were minor drug dealers no longer considered a threat.

Obama has promised to use his clemency powers to help serve penal justice, rather than to grant special favors.

"I don't think we will see high-profile names on the list of President Obama's final clemency grants," Mark Osler of the University of St. Thomas told AFP.

"It is most likely they will be the types of cases he has previously commuted: nonviolent narcotics offenders."

He noted that last-minute clemency is a recent phenomenon.

"Up until President Clinton, they usually spread them out over their full term. Hopefully, in the future presidents will return to that practice, which seems less prone to abuse," Osler said.

Presidents can theoretically pardon people before they are even sentenced.

In 1868, president Andrew Johnson granted a "full pardon and amnesty" to Confederates of the 11 southern states who unsuccessfully fought the Civil War to secede from the union.

Citing this precedent, some have urged Obama to preventively pardon defeated Democratic presidential candidate Hillary Clinton over her use of a private email server while serving as secretary of state in light of Trump's threats to have her prosecuted.

Obama could also be tempted to grant amnesty to his onetime "favorite general," James Cartwright, who lied to the FBI about his discussions with journalists about Iran's nuclear program.

Some pardon requests can be far-fetched, such as one for the late Marcus Garvey, a Jamaican political leader who backed Pan-Africanism and helped inspire the Rastafarian movement.