MOSUL, Iraq - Ibrahim Al Jaburi and Mashaan Al Jaburi are both leaders of the Al Jabur, the country's largest and most powerful tribe, and both want to become president of Iraq. One of them has his money on tradition, the other on modernity.

Ibrahim, 56, wears billowing black robes with gold trim, a flamboyant handlebar moustache, and a white head cover. Each day he receives petitions from tribesmen in his diwan, the time-honored meeting place of tribal leaders, resolving disputes and finding work for unemployed young men. In the afternoon, he and a dozen or so guests feast on an elaborate lunch of roasted lamb, flatbread, and rice served on a huge platter. Visitors help themselves to handfuls of meat and rice, taking care to save the lamb's brains for that day's guest of honor.

Ibrahim Al Jaburi receiving tribal leaders in his cell block.

Mashaan, 46, is the son of a prominent Jaburi sheik. He wears a short-sleeved khaki shirt with a zippered front. He lives in a villa formerly owned by one of Saddam Hussein's senior henchmen. And he spends much of his day on a computer writing memos to aides and editing columns for a daily newspaper he owns and prints in Syria.

A well-armed security detail forms a floating perimeter around him as he strolls through a garden that unfolds onto the Tigris. Mashaan serves his guests beer with lunch; cooked brains of any kind aren't on the menu.

Ibrahim and Mashaan Al Jaburi are different products of the same tribal elite vying for control of a country trying to define itself after years of oppression.

The momentum, for now, seems to be with Ibrahim and his ancient ways. With Hussein gone, the US occupation facing many challenges, and Iraq's political parties in their infancy, the country's most important power center remains the tribes. Although largely urbanized, three-quarters of all Iraqis are members of tribes and tribal identity has intensified since the early 1990s, as Baghdad's authority buckled under the United Nations embargo imposed after Iraq invaded Kuwait. The tribe delivers services like health and education, and its sheik employs a network of contacts and resources that would be the envy of any political boss in late 19th-century New York or Chicago.

"We are preparing to become part of society as a political group, not merely as a tribe," said Ibrahim, who like all political leaders in Iraq today is long on platitudes and short on policy positions. "A party with [2 million] members could be the most powerful party of all."

Ibrahim and his contemporaries see themselves first as members of tribes - benevolent autocracies governed by a medieval code that demands obedience in return for effective leadership. It is a system that predates Islam and has weathered centuries of imperialism, dictatorship, and friction between Iraq's Sunni and Shia religious groups.

Mashaan regards himself as an Iraqi. He said the tribal code in postwar Iraq will soon be replaced by a constitution and a rule of law enforced equitably by the state. Having spent one career working the gears of tribal affairs, he now spends more time with US occupation officials than he does with his fellow Jaburis, who account for just under 2 percent of Iraq's total population of 24 million.

"I would be ashamed to be a part of a tribe," Mashaan said from a garden once inhabited by Ali Hassan al-Majid, known as "Chemical Ali" for allegedly using poisonous gas to kill thousands of Kurds in a 1988 revolt against the regime. "The people who say they are of a tribe are of a low education," Mashaan said.

But in this formative stage of Iraqi democracy - particularly with most Iraqis preoccupied with shortages of electricity, security, and clean water - it is the tribes and their formidable networks that get respect. When Colonel William Bishop, director of the 101st Airborne's civilian-military operations in Mosul, was called upon unexpectedly two weeks ago by a prince of the Al Yazidi tribe, he cut short his morning shower and met with the clan leader for 30 minutes. At a meeting last week between senior US officials and tribal leaders to address postwar conditions in Baghdad, the sheiks gave the Americans a dressing down. The Americans, according to a participant, took it.

Should democracy take hold in Iraq, leaders of important tribes like the Al Jabur could emerge as important spoilers, kingmakers - even heads of state. "Once you get here, you understand just how strong tribal influence is in society," Bishop said. "And the Al Jaburis are particularly strong."

That assumes the tribe can survive democratization; Mashaan Al Jaburi is betting it won't. Unlike Ibrahim, who speaks only Arabic and rarely travels beyond his fiefdom, Mashaan speaks fluent English as well as the strategic cant of modern politics. In a country scarred by clan, sectarian, and ethnic divisions, Mashaan appeals to Iraqi nationalism before tribe, religion, or ethnicity. While Ibrahim and his family have been a fixture in Mosul for decades, Mashaan has operated largely from exile, where he struck alliances with Kurdish warlords and Syrian businessmen. He helped US forces in Mosul arrange local elections but did not contest them, saving himself for a national stage.

Few Iraqis had ever heard of Mashaan Al Jaburi until they began seeing him on television and reading his newspaper, Alitijah al-akhar. "I've seen him two or three times," said Khalef Zidan, who runs a transportation company in Baghdad. "He speaks well. He has money. He seems to have a vision for the future the rest of the parties don't have."

The political free-for-all that followed Hussein's ouster appears to have set Ibrahim and Mashaan into confrontation personally as well as politically; Ibrahim was arrested and jailed for two weeks following the surrender of Mosul by US occupation forces on information he was responsible for a looting spree that involved stolen cars.

Ibrahim dismissed Mashaan as a carpetbagger with no more legitimacy than other exiles who followed the Americans into Iraq after spending years in comfort elsewhere. He seeks to build a political party with the Al Jabur - a constituency that includes doctors, engineers, and teachers - at its core. In Baghdad last month, Ibrahim and several hundred leading Jaburis flexed their political muscle at a tribal congress.

Compromise and coalition-building should come naturally to a traditional sheik like Ibrahim, who has spent most of his life mediating everything from petty claims to murders and rapes. When not deliberating in a diwan, he doles out funds to his tribe for new roads, water projects, and hospitals. The money for such largesse used to come from Hussein, who over the past decade became increasingly dependent on tribal leaders to subdue potential threats to his regime.

Ibrahim once deployed his tribesmen on Hussein's behalf. After the first Persian Gulf War, when tribes in southern Iraq rose to topple the regime, it was Jaburi sheiks like Ibrahim who helped defeat them. In 1993, Hussein launched a campaign to rein in the increasingly powerful Jabur.

"He wanted to have us for lunch before we had him for dinner," Ibrahim said.

Ibrahim was invited along with several other sheiks to a dinner hosted by Hussein's close friend, who harangued them for alleged disloyalty. Incensed, Ibrahim pulled a gun and shot the man four times, leaving him for dead, although he recovered. The incident sparked a blood feud between Hussein loyalists and Jaburi clansmen within the army that lasted months. Ibrahim was arrested but, with the help of his tribal connections, quickly escaped north to Mosul. An uneasy truce followed, during which Hussein slowly replaced Jaburi officers with members of the Al Duleim, the Jabur's bitter rival.

Mashaan, too, was once a Hussein ally, only to find himself on the wrong side of his wrath. In 1974, he was "appointed" by the dictator as a midlevel sheik, a tactic used by Hussein to play tribal factions against each other. During Iraq's 1980-88 war with Iran, Hussein ordered Mashaan to find recruits who were willing to sacrifice themselves for the regime.

Mashaan led a convoy of buses to his hometown near Tikrit, Hussein's birthplace, and returned to the dictator with thousands of volunteers. If few of them were willing to die for Hussein, Mashaan said, they were willing to die for their tribal honor.

"They knew they probably wouldn't come back alive, but to refuse service would be to shame your family," Mashaan said. "Saddam understood this."

In 1989, angered by Hussein's lack of gratitude for the Jaburs' sacrifice, Mashaan said he agreed to participate in a coup against the regime. By December, there were signs the plan had been compromised, and Mashaan fled for a life in exile and eventually settled in Damascus where he launched the Iraqi Homeland Party.

Mashaan is close to the regime in Syria and said he was instrumental in the opening of the Rabieh border crossing - although tensions stirred when Mashaan and his family crossed there from Syria 10 days ago and his bodyguards refused to check their weapons. He is strongly allied with the Kurdish Democratic Party, one of two groups that govern Iraq's northern Kurdistan.

The Iraqi Homeland Party will soon move its headquarters from Mosul to Baghdad, Mashaan said, which he will staff with Arabs, Kurds, Shi'ites, and Sunnis. Iraqis all, he said - not tribesmen.

"I am from the city, not from the tribe," Mashaan said. "I am an Iraqi first, second, and third. That is the future of Iraq."