Last August, when Barack Obama introduced Joe Biden as his choice for vice president, he praised the Delaware senator's strength in foreign policy and defense issues -- areas widely thought to be weaknesses in Obama's resume. 

"Joe Biden is what so many others pretend to be -- a statesman with sound judgment who doesn't have to hide behind bluster to keep America strong," Obama said at the time.

But five months into his vice presidency, Biden appears to have been pushed into the background, focusing on overseeing the implementation of Obama's $787 billion stimulus package, the creation of jobs and other domestic matters as the president and former rival Hillary Clinton -- and even former Sen. George Mitchell -- deal with the growing crises in Iran and North Korea, wars in Iraq and Afghanistan, and rewriting the way America deals with a hostile Muslim world.

By comparison, Biden's predecessor, Dick Cheney, was after five months already being called the most influential vice president ever. Even though Cheney didn't face any immediate crises at the outset of the Bush administration, he arguably became a co-planner in the U.S. war on terror after the Sept. 11 terrorist attacks.

Five months into the job, as different as Obama is from Bush, there appears to be an even more dramatic difference between Biden and Cheney. 

"Joe Biden is Mr. Outside and Dick Cheney was Mr. Inside," said Lee Edwards, a presidential historian at the Heritage Foundation, who described Biden as very visual and vocal while Cheney worked behind the scenes. 

"I would say we don't really know how much influence Biden really has, whereas early on we knew Cheney wielded significant power," Edwards said.

Even now -- in "retirement" -- Cheney appears to be grabbing more headlines than Biden as he has repeatedly criticized Obama's national security policies, arguing that they are making the United States less safe.

Biden fired back in April, asserting that Cheney was "dead wrong" and that the exact opposite is true. He added that Cheney had been part of a dysfunctional decision-making system in the Bush administration.

"Look, everybody talks about how powerful Cheney was," Biden said. "His power weakened America, in my view. Here's what I mean by that. What I mean by that was, there was a divided government."

He added that Cheney had his own sort of national security council, in addition to the actual National Security Council, and that Cheney would side with Defense Secretary Donald Rumsfeld in disputes with Secretary of State Colin Powell.

But since then, Biden has slipped back into the background, delivering a few commencement speeches, officiating at a groundbreaking ceremony for the start of his "Road to Recovery" tour, and apparently not being part of the inner circle on foreign policy -- the field of expertise that was the basis for his selection.

Instead Biden has promoted his role in Obama's administration as that of a catalyst to better decision-making.

"The strength of this administration is that the president and I work in concert," he said. "I am very straightforward in my views. I am as strong ... I hold them as strongly as I ever have."

Biden declared early this year that he intended to "restore the balance" of power between the presidency and vice presidency, something he claims Cheney upended.

Instead Biden has been attending economic meetings and taking light-fare overseas trips, including to Germany and Latin America.

Biden also heads the Task Force on Middle Class Working Families. But he's drawn far more attention for his political blunders, including a hotly disputed claim that he privately rebuked Bush when he was president.

In contrast, five months into Cheney's vice presidency, after running Bush's transition team, he was operating out of four offices -- two on Capitol Hill by virtue of his role as president of the Senate.

Cheney also was the point man in two of Bush's biggest pre-9/11 priorities: energy and missile defense. He also was a potential tie-breaking vote in a closely divided Senate.

Shirley Ann Warshaw, a presidential historian at Gettysburg College and author of the new book, "The Co-Presidency of Bush and Cheney," said Biden has been used as vehicle to deliver the Obama administration's message, while Cheney crafted the Bush administration's.

"Delivering the message and crafting the message are very different things," Warshaw told FOXNews.com, noting that Biden was largely excluded from Obama's transition while Cheney hired virtually everyone.

"There will never be another vice president to match Dick Cheney," she said.

Warshaw said Biden doesn't hold as much sway as Cheney did because Obama has a strong team of inside players, led by White House chief of staff Rahm Emanuel and senior policy adviser David Axelrod.

"President Bush did not have a political insider as a sounding board to the equivalent of Rahm Emanuel," she said.

And when it comes to foreign policy, considered Biden's greatest strengths, Warshaw said Secretary of State Hillary Clinton "is wary to give him too much leeway."

Another factor, Edwards told FOXNews.com, is that "Biden was and is a creature of Congress, while Cheney is a more skilled practitioner in the executive branch."

"I think Biden, by reason of being a senator, is a loner, even within in the party," he said. "I don't know if he represents a significant part of his party. Cheney still represents a significant part of his party."

Edwards said history will view Biden "as a rather typical vice president, somebody who was chosen because it was felt he would bring some balance and some strength to the campaign and help the presidential candidate win. And that's the case with more vice presidents than not."

But Edwards added that each man was perhaps the best fit for each president.

"I think that Cheney was what Bush needed because he had the experience and the knowledge and could get things done," he said. "I think Obama came to the presidency with the agenda already set. He knew what he wanted to do. In that sense, he hasn't need a strong guy as Bush did."