An audiotape purportedly from Usama bin Laden suggests the Al Qaeda chief has accepted Abu-Musab al-Zarqawi's (search) offer to unite the world's most famous terror group and the bloodiest insurgency inside Iraq, national security experts say.

Bin Laden could benefit from allying himself with an anti-American fighter who gets daily publicity. Al-Zarqawi may get more financial assistance and support from bin Laden's backers, the experts said.

But for bin Laden, the alliance comes at a price: He is now tied to a man directing bomb attacks against Iraq's majorityShiite Muslims (search) as well as Americans.

In an audiotape broadcast Monday by Al-Jazeera satellite television, the man appearing to be bin Laden described al-Zarqawi as the "emir," or prince, of Al Qaeda (search) in Iraq and said Muslims there should "listen to him." He also called for a boycott of Iraqi elections planned for next month.

"Bin Laden gets the benefits of Zarqawi's notoriety," said Vince Cannistraro, former CIA counterterrorism chief. "He (al-Zarqawi) has got the pre-eminent insurgency in Iraq. He's the one who is the bloodiest, who carried out the most dramatic and public suicide bombings."

The difference between this and other bin Laden alliances, Cannistraro said, is that bin Laden — a Sunni Muslim — "has not been a vocal enemy against the Shiites. By adopting Zarqawi, he's taking that whole package, someone who is virulently anti-Shiite."

The CIA said Monday it had not yet identified the man on the tape as bin Laden.

Dr. Bruce Hoffman, a terrorism expert at the Rand Corp., said al-Zarqawi also gets an advantage by association with his former rival.

"Zarqawi tried to milk his broader association with bin Laden and Al Qaeda to win new sources of support and recruits and finances," Hoffman said.

Hoffman, whose company is known for its problem-solving research, agreed that both men benefit from the alliance.

"I think bin Laden wants to leverage off of Zarqawi's cachet and popularity amongst radial jihadists," he said. "Zarqawi realizes that his association with Al Qaeda and bin Laden — perhaps not in tangible terms in the fighting in Iraq — but in terms of support and assistance can pay vast dividends."

Ben Venzke, president of the private IntelCenter in Alexandria, Va. and a consultant to government agencies, said the alliance does not demonstrate any weakness by bin Laden. Rather, it enhances his public message.

"Al Qaeda is very savvy when it comes to understanding public perception, its media campaign and messaging and its image," he said.

"There is no question, and I think it would be safe to presume, that Al Qaeda understands that if they officially tie that name (al-Zarqawi) in, it gives them an even greater media presence in terms of operations that are being conducted."

In calling for a boycott of elections, bin Laden appears to also be speaking as a political leader, not just a terrorist going into battle.

The speaker on the tape said, "In the balance of Islam, this constitution is infidel and therefore everyone who participates in this election will be considered infidels. Beware of henchmen who speak in the name of Islamic parties and groups who urge people to participate in this blatant apostasy."

Roger Cressey, who was the deputy to former White House counter-terrorism chief Richard Clarke, said the boycott message indicates bin Laden has been trying to broaden his audience.

"He is trying to position himself as speaking to a global Islamic community in a way that further defines the fight against the West in his terms," Cressey said.

"If he can show he's more than just a rank-and-file terrorist, that will help his message."

Cressey said bin Laden is trying to reach "the part of the Muslim world that is sympathetic to the message, but is not willing to endorse him. These are fence sitters, people who have serious problems with the U.S. policy but have not become activists against us yet."

Peter Bergen, a fellow at the New American Foundation, a Washington think tank, says he doesn't believe bin Laden's call for a boycott will have much effect because most of the Sunnis against the election already were planning to shun the polls. "It's just one more reason to boycott it," he said.

With the release of still another bin Laden tape, Bergen said, "The tapes are coming thick and fast, which means they (the terrorists) are feeling secure."