CAIRO, Egypt – In an audiotape broadcast yesterday by Al Jazeera satellite TV, a man purported to be Osama bin Laden endorsed Abu-Musab al-Zarqawi as his deputy in Iraq and called for a boycott of next month’s elections there.

The new tape, together with one that appeared online earlier this month, continues a new political slant adopted by the Al Qaeda leader, whose past proclamations have been more a call to arms than a promotion of a cause. They appear to back up recent suggestions by Middle East experts that Mr. bin Laden may be trying to become more of a political leader than a terrorist.

The voice on the tape described Mr. al-Zarqawi as the “emir,” or prince, of Al Qaeda in Iraq and said Muslims there should “listen to him.”

The man speaking on the tape also referred to an October statement in which Mr. al-Zarqawi, a Jordanian, declared allegiance to Mr. bin Laden and changed his group’s name to Al Qaeda in Iraq. The speaker called that “a great step on the path of unifying all the mujahedeen in establishing the state of righteousness and ending the state of injustice.”

The voice on the tape broadcast yesterday sounded like Mr. bin Laden’s and the statement used language that appeared to conform with previous statements by the Saudi-born terror mastermind. However, there was no way to independently confirm the speaker’s identity.

In Washington, U.S. State Department spokesman Adam Ereli said it had not been determined whether the speaker was Mr. bin Laden but “it’s a message from terrorists” and an attempt “by murderers to propagate their evil trade.”

Al Jazeera broadcast excerpts of the tape while showing a still photo of the bearded bin Laden, wearing a white robe and head covering.

An Al Jazeera announcer said the speaker on the tape also called for attacking pipelines, planting mines, and killing people who work for the occupation forces.

Mr. al-Zarqawi’s group is believed responsible for numerous car bombings and beheadings of foreign hostages in Iraq.

Mr. al-Zarqawi is believed to have escaped from his headquarters in the insurgent-held stronghold of Fallujah during the massive American-led assault in the Iraqi city last month.

The speaker said Mr. al-Zarqawi and those with him are fighting “for God’s sake.”

“We have been pleased that they responded to God’s and his prophet’s order for unity, and we in Al Qaeda welcome their unity with us,” the speaker said. The speaker also said he was “pleased” with Mr. al-Zarqawi’s “gallant operations” against the Americans and Prime Minister Allawi’s “apostate government.”

Iraqis are scheduled to elect a 275-member National Assembly on January 30, and those lawmakers will draft a new constitution. The speaker condemned those elections.

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

He apparently was referring to Shiite clerics, particularly Grand Ayatollah Ali al-Sistani, who have issued edicts saying participating in the election was a “religious duty.” Al Jazeera spokesman Jihad Ballout refused to say how or when the station received the audiotape.

Separately, a suicide car bomber killed 15 people yesterday in an attempt to assassinate the head of Iraq’s strongest Shiite party before parliamentary elections next month, while the biggest Sunni Muslim political group dealt a blow to ballot plans by withdrawing from the campaign because of the lack of security.

The bomber tried to drive his car through the gate at the home of Abdul Aziz al-Hakim, leader of the Supreme Council for the Islamic Revolution in Iraq, but detonated his explosives when guards blocked the way.

Fifteen people died and at least 50 were wounded in the explosion, which shook Baghdad’s Jadiriyah district and sent a cloud of smoke billowing into the sky, police Captain Ahmed Ismail said. Mr. al-Hakim, who was inside, was not hurt.

Mr. al-Hakim heads the 228-candidate list of the United Iraqi Alliance, which includes parties and individuals from all Iraqi ethnic and religious groups but is dominated by Shiites, who account for about 60% of the country’s population. Backed by Ayatollah al-Sistani, the coalition is widely expected to dominate the post election constitutional assembly and play a key role in formulating Iraq’s new national charter.

Just hours after the blast, the leader of a moderate Sunni bloc, the Iraqi Islamic Party, announced that the group had reversed its earlier decision to take part in the January 30 elections.

In other developments, two American soldiers were killed by separate roadside explosions, the military said yesterday.

One soldier died and a second was wounded when a bomb hit a patrol in Samarra, 60 miles north of Baghdad. Another soldier was killed and four were wounded by a bomb in Baghdad.