Just what did Barack Obama mean when he said John McCain was "losing his bearings?"

The two campaigns got in a strange tussle Thursday night over those words, with the McCain camp accusing Obama of taking a cheap shot at the Arizona senator's age.

Obama used that phrase during an interview with CNN, when he accused McCain of trying to smear him by suggesting that Hamas preferred Obama for president.

McCain adviser Mark Salter swiftly sent out a lengthy memo claiming Obama was trying to divert attention from real issues by resorting to ageism.

"He used the words 'losing his bearings' intentionally, a not-particularly-clever way of raising John McCain's age as an issue," Salter said. "This is typical of the Obama style of campaigning."

The expected Republican presidential nominee turns 72 in August, and would be the oldest person sworn in as president if elected.

But the Obama campaign did a double-take at Salter's memo, which the campaign dubbed a "rant."

"Clearly losing one's bearings has no relation to age, given this bizarre rant that Mark Salter just sent out," Obama spokesman Bill Burton said. "It's clear why a candidate offering a third term of George Bush's disastrous economic policies and failed strategy in Iraq would want to distract and attack, but it's not the kind of campaign John McCain has promised the American people that he would run."

At the root of the dispute is McCain's decision to call attention to a Hamas adviser's apparent affinity for Obama. The adviser, Ahmed Yousef, said in a recent interview: "We like Obama and hope that he will win the election."

McCain used those comments in a fundraising appeal and has cited them in interviews.

Asked about the matter Wednesday during a taping of "The Daily Show with Jon Stewart," McCain said: "It's indicative of how some of our enemies view America. And I guarantee you, they're not going to endorse me."

In Obama's CNN interview, he accused McCain of engaging in a smear campaign.

"This is offensive, and I think it's disappointing, because John McCain always says, 'Well, I'm not going to run that kind of politics.' And then to engage in that kind of smear, I think, is unfortunate, particularly since my policy toward Hamas has been no different than his," Obama said.

The Illinois senator added: "For him to toss out comments like that, I think, is an example of him losing his bearings as he pursues this nomination. We don't need name-calling in this debate."

The Associated Press contributed to this report.