Osama bin Laden is dead and gone but his demise was trotted out Friday as a campaign issue by President Barack Obama, whose new ad questions whether his Republican rival would have ordered such a risky military raid.

The video features ex-president Bill Clinton hailing Obama for a brave call to take out the Al-Qaeda leader in a Navy SEALs operation one year ago.

Aides to White House challenger Mitt Romney and a top Republican rapped Democrats for politicizing the raid in the run-up to its May 2 anniversary, saying it was "unbecoming" of Obama to reduce the historic moment to a campaign slogan.

"He had to decide. And that's what you hire a president to do. You hire the president to make the calls when no one else can do it," Clinton said in the 90-second video, which sought to contrast Obama with the presumptive Republican nominee.

Entitled "One Chance," the ad uses images of Obama and his cabinet in the White House Situation Room, and news footage including quotes from Romney during his 2008 failed presidential bid in which the former Massachusetts governor appeared ambivalent about going after the elusive bin Laden.

Clinton saluted Obama for greenlighting the clandestine raid in Pakistan despite knowing that the consequences would be disastrous if it went wrong.

"Suppose the Navy SEALs had gone in there, and it hadn't been bin Laden," Clinton said.

"Suppose they'd been captured or killed. The downside would have been horrible for him.

"But he reasoned, 'I cannot in good conscience do nothing.' He took the harder and the more honorable path, and the one that produced, in my opinion, the best result."

The operation plunged US-Pakistani ties to an all-time low but it was seen as a huge strategic and popular success for Obama given the decade-long hunt for the terror mastermind.

The ad's on-screen text asks: "Which path would Mitt Romney have taken?" and features a screen grab highlighting Romney's doubts about the merits of searching for bin Laden.

"It's not worth moving heaven and earth spending billions of dollars just trying to catch one person," Romney was quoted as saying in a news report shown on CNN from when he was a Republican candidate four years ago.

Vice President Joe Biden had seized on the same remarks Thursday in a foreign policy speech.

"If you're looking for a bumper sticker to sum up how President Obama has handled what we inherited, it's pretty simple: Osama bin Laden is dead and General Motors is alive," Biden said.

The White House pushed the narrative even further on Thursday, when Obama gave a US network an extraordinarily rare interview in the Situation Room and discussed the key moments in the dramatic run-up to bin Laden's demise.

"This is another window into that remarkable day," National Security Council spokesman Tommy Vietor said.

Romney's campaign argued that while Romney congratulated the president and military on that day last year, a "desperate" Obama was seizing on the achievement to distract voters "from the failures of his administration."

"Killing Osama bin Laden was a momentous day for all Americans and we all give the president credit," former defense secretary Frank Carlucci and former navy secretary John Lehman, who both served under president Ronald Reagan, said in a Romney campaign statement.

"But we are saddened to see the president of the United States politicize that event, even reducing it to a campaign slogan. This is unbecoming of the commander-in-chief."

Romney's campaign attacked Obama's "remarkably flailing" reelection bid, saying the president is refusing to run on his record.

So did Senator John McCain, who beat Romney to the Republican nomination in 2008 but lost the election to Obama.

"Shame on Barack Obama for diminishing the memory of September 11th and the killing of Osama bin Laden by turning it into a cheap political attack ad," McCain said in a statement.

He listed a litany of administration failures, including not supporting the Iranian opposition that was crushed in 2009, attempting to try 9/11 suspects in New York, pulling out of Iraq and announcing the US departure from Afghanistan.

"With a record like that on national security, it is no wonder why President Obama is shamelessly turning the one decision he got right into a pathetic political act of self-congratulation," McCain said.