Both want to close the controversial U.S. military detention facility for terrorism suspects at Guantanamo Bay, Cuba, and try such defendants elsewhere.
And both have come to support legislation that ensures at least some court oversight of the electronic eavesdropping in terrorism investigations to protect the privacy of American citizens.
And neither has said much about reforming the intelligence community or the Department of Homeland Security.
One advisor to Obama, a counter-terrorism expert, attributes to presidential campaign politics the disconnect between the perception of the candidates and their policies.
Both candidates, he said, are happy to talk tough on terrorism and to criticize their opponent. But they are reluctant to talk specifics because it is there -- in the nuts and bolts of how to fight Al Qaeda and the spreading ideology of anti-Western Muslim extremism -- where the controversies lie and the risk of alienating voters is potentially great.
"There is not a big incentive to articulate the details. These are complex questions that don't lend themselves to short answers during presidential debates," said the advisor, speaking on condition of anonymity because his role in the campaign is not public.
But Randy Scheunemann, McCain's senior national security advisor, said that the two candidates are "profoundly different on a range of issues."
Scheunemann said Obama "refused to see the obvious that Iraq was the central front in the war on terrorism," whereas the Obama campaign said McCain erred in emphasizing Iraq over the terrorism problem in Afghanistan.
Officials with both campaigns acknowledge that the two candidates' positions have grown closer on at least some security issues in recent months, in part because of the improving security situations in Iraq and deteriorating stability of Afghanistan and Pakistan.
"The reason people think there is a coming together is because McCain has been forced to move on issues like Iraq and Afghanistan in Obama's direction, because the world has moved in that direction," said an Obama national security advisor, Richard Clarke, a former Clinton and Bush administration counter-terrorism official.
And both camps say that despite any similarities on paper, there are fundamental differences in the candidates' approach to counter-terrorism, which stem from how they see themselves and the world at large.
