A senior advisor to presumptive Republican presidential nominee Mitt Romney on Sunday accused Barack Obama of being "one of the most divisive presidents in American history" for making the killing of Osama bin Laden a part of his re-election campaign.

"He took something that was a unifying event for all Americans – an event that Gov. Romney congratulated him and the military and the intelligence analysts in our government for completing the mission in terms of killing Osama bin Laden – and he’s managed to turn it into a divisive partisan political attack," Romney aide Ed Gillespie told NBC's David Gregory.

In a major speech on Wednesday, Vice President Joe Biden recalled that Obama had “made one of the most courageous decisions” he had ever seen a president make by ordering the strike on the terrorist mastermind.

“This guy has a got a backbone like a ramrod,” the vice president said. “For real. For real. On this gut issue, we know what President Obama did. We can’t say for certain what Governor Romney would have done.”

“Thanks to President Obama, bin Laden is dead and General Motors is alive,” Biden continued. “You have to ask yourself had Governor Romney been president, could he have used the same slogan in reverse?”

Gregory noted on Sunday that former Vice President Dick Cheney had used imagery from the Sept. 11 attacks and made the case in 2004 that the country would be less safe if Sen. John Kerry (D-MA) were elected instead of President George W. Bush.

"So is it any different?" Gregory wondered.

"We can go back an talk about -- what's that eight years ago? -- the record of Sen. Kerry," insisted Gillespie, who was chairman of the Republican National Committee in 2004. "This is an attack on something that might not have happened. You know, it's a bridge too far. I think that the American people will see through it."

"Is American safer under President Obama's leadership?" Gregory pressed.

"We may be -- I think we're safe," Gillespie admitted. "We haven't been subject to attack, but I don't know that's -- I'm not sure. I don't know enough in terms of the intelligence. I used to know that. But I don't believe that President Obama -- under President Obama -- we are as strong as we should be as a nation."

The Associated Press quoted Romney in 2007 as saying that there would be only “a very insignificant increase in safety” if bin Laden were killed.

“It’s not worth moving heaven and earth spending billions of dollars just trying to catch one person,” Romney reportedly said.

But speaking to Fox News late last year, Romney insisted that “any president” would have given the order to take out the 9/11 architect.

“We’re delighted that he gave the order to take out Osama bin Laden,” the former Massachusetts governor told host Chris Wallace. “Any president would have done that, but this one did, and that’s a good thing. I’m not going to say everything he’s done is wrong.”

Watch the video below from NBC's Meet the Press, broadcast April 29, 2012.