A group of former top military officers has played a crucial — but largely overlooked — role in the presidential campaign of Sen. Barack Obama (D-Ill.), helping him shape his national security policies and defending the first-term Senator against charges that he lacks the experience to be commander in chief.

“I think the campaign feels it’s important to show that the uniformed military respects Obama,” said Whitten Peters, a former secretary of the Air Force who is an adviser to the Obama campaign on national security issues.

The group of about 60 former Army, Air Force and National Guard generals and Navy admirals, known among campaign insiders as the senior officers group, has been providing advice to Obama for about six months. Much of their work has been done online by sharing ideas on defense and foreign policy, although in July the group held a “summit” in Washington, D.C., about how they could coordinate efforts over the fall campaign.

There is no formal leadership structure for the senior officers group, but former Air Force Gen. Tony McPeak and former Air Force Maj. Gen. Scott Gration have the most visible roles of any officers helping the Obama campaign. Both say they were courted by Obama and won over by his intellect, integrity and call to end the Iraq War.

Gration, a former Air Force fighter pilot who flew nearly 300 missions over Iraq in the first Persian Gulf War and grew up the son of missionary parents in Congo, first met Obama when he briefed him on NATO issues in 2005. The two became close a year later when Gration accompanied Obama on a visit to Africa that included stops in Obama’s father’s homeland of Kenya and a visit to the former South African prison cell of Nelson Mandela.

“As I watched him I saw a man of tremendous integrity. It was very clear that we shared the same values,” said Gration, who considered himself a political independent before becoming an adviser to the campaign after leaving the military in 2006. He went on 13-day speaking tour in Iowa last summer to improve Obama’s credibility on national security.

McPeak, who served as Air Force chief of staff for the first President Bush and was a onetime War College classmate of presumptive GOP presidential nominee Sen. John McCain (Ariz.), said Obama asked to meet with him in early 2007 based on his outspoken support for the campaign of the anti-war candidate Howard Dean in 2004. Like Gration, McPeak came away impressed, endorsed Obama almost immediately and is now listed as a co-chairman for the campaign.

“He was clearly the candidate who saw this Iraq War was a loss from the start,” said McPeak, who voted for Bush in 2000 and was the chairman of Bob Dole’s Oregon presidential campaign in 1996. “He’s got leadership qualities I wish I had. Barack Obama is electric and that comes through in person.”

The former generals’ most visible role came in March when they were among a group of 10 retired military officers who appeared with Obama at a press conference, where he addressed campaign ad attacks from his primary rival Sen. Hillary Rodham Clinton (D-N.Y.) that he lacked the experience to become commander in chief.

Appearing at the press conference with the candidate, McPeak memorably praised the Senator as having the right temperament to lead the military, calling him “no drama Obama.” Gration was even more blunt, saying Clinton “supports the Bush policy of not talking to leaders we don’t like and gave George Bush the benefit of the doubt on Iran and Pakistan. On these key questions, Barack Obama not only made a different judgment — he made the right judgment.”

Obama’s deft response to those attacks was viewed as a turning point in the campaign and one that campaign aides believe helped put him on a path to the nomination. McPeak said the handling of the attack proved his point that Obama does not panic under pressure.

David McGinnis, a former Army National Guard general who has also been active in the senior officers group, said that aside from media appearances and speaking at campaign events, the group’s members do a lot of vetting of national security policies and field questions from the campaign and Obama himself. The group has discussed topics with Obama and his campaign ranging from the economy as an instrument of national power to the nation’s space policy, McGinnis and other officers said.

McGinnis and other senior officers interviewed for this article said it was not yet clear whether they would take on a broader role in the campaign. At the convention tonight, Democrats are set to highlight national security issues, but none of the former generals are expected to be on the podium and some might not even be in Denver. “If the key issue is the economy this fall, then maybe we will stay muted,” McGinnis said.

Still, Gration said there is a symbolic role that the officers play by backing Obama over McCain, who has deep ties to the military as a Naval Academy graduate, the son of an admiral, a fighter pilot and prisoner of war in Vietnam. “People will look at [military issues] and say ‘if generals say Obama’s plans are OK, then they must be OK,” Gration said.

Gration and McPeak both have been mentioned as potentially in line for key Defense or State department jobs in an Obama administration. Both say they do not expect jobs and already are involved with existing business ventures.