DAMASCUS, Syria — Tens of thousands of mourners, waving black banners and wailing with grief, took to the streets on the eve of President Hafez Assad's state funeral, while Syria's powerful military closed ranks behind the late leader's son and heir apparent, Bashar Assad.

Photos of Bashar Assad in military fatigues were plastered on walls all over Damascus — underscoring vital support of the armed forces for the computer-savvy, Western-educated son Assad had groomed for the past six years as his successor.

But despite speedy moves by the Syrian hierarchy to ensure his ascent to power, it remained to be seen whether Bashar Assad, an eye doctor who has never held a major political post, would be tough and canny enough to survive as leader. During three decades of autocratic rule, his father often employed ruthless measures to quell any challenge.

The long-term impact on any comprehensive Middle East peace accord was also uncertain. Israeli-Syrian peace negotiations, briefly revived late last year after a four-year hiatus, are now likely to remain stalled during the transition period.

Syria and Israel remain technically at war, but their frontier has been quiet for years and has remained so since Assad's death Saturday at the age of 69.

Throughout the Syrian capital Monday, shops were shuttered, with almost the only business being done by vendors selling black mourning cloth by the yard for banners and flags. Mourners flooded in from the countryside, some on horseback and clad in traditional dress.

Crowds walked in rows through the street, with women weeping and people waving portraits of Hafez Assad. Others carried black banners emblazoned, "Bashar, the hope of millions." Black flags hung from balconies and drivers tied black strips of cloth to car antennas.

Within 24 hours of Assad's death being made public, Bashar Assad's anointment as leader was well under way. On Sunday, the ruling Baath Party nominated him for president, after the constitution was amended to lower the required age for the post to 34 — his age — from 40. All that is left is for the rubber-stamp parliament, scheduled to meet June 25, to approve the nomination and for elections to be held.

Also Sunday, the younger Assad was named commander in chief of the military and elevated from colonel to lieutenant-general. He then received a key visit from the defense minister and other military officials, who "pledged their loyalty," according to the official Syrian news agency.

"Now we have a sole candidate for the presidency and there is popular unanimity and this is clear from the demonstrations and the people's emotions," Defense Minister Mustafa Tlass told the Lebanese television station Future on Monday.

Seeking to stifle any potential challenge, Syrian authorities reportedly planned to arrest Rifaat Assad — the exiled brother of the late president, who had tried to stage a coup in 1983 — if he tried to return.

The London-based Arabic-language daily Al-Hayat cited a senior Syrian official, who spoke on condition of anonymity, as saying Syria's military and intelligence were "fully authorized to take any measure" to prevent Rifaat Assad, exiled since 1984, from entering the country.

No official confirmation of the report could be obtained in Damascus. Rifaat Assad has reportedly been living in France and Spain, but his whereabouts were unknown.

Assad biographer Patrick Seale, who was close to the late leader, expressed confidence that the younger Assad's leadership was secure. Writing in Monday's editions of the London-based Arabic daily Al-Hayat, he noted that "expected challengers have been neutralized or their reputation tarnished."

Damascus, meanwhile, prepared for Tuesday's state funeral, expected to be the largest such gathering of modern times in Syria. World dignitaries, including Secretary of State Madeleine Albright and British Foreign Secretary Robin Cook, were flying in to attend.

Street-sweepers and painters were hard at work in front of Omayyad Square in Damascus, where the late president's body was to lie in state before being taken to his home village of Qardaha, 125 miles northwest, for burial.

In neighboring Israel, hundreds of Druze Arabs wanting to attend the funeral tried to cross from the Israeli-occupied Golan Heights into Syria, waving pictures of Hafez Assad in the faces of Israeli soldiers, who pushed them back. A group of 100 had Israeli permission to cross, but when Syria said it would allow only 59 of them in, the delegation declined to go.

Bashar Assad had been quietly practicing ophthalmology in Britain until the sudden 1994 death of his older brother Basil, who was widely believed to have been his father's first choice as heir. He returned to Syria and was groomed to take his father's place, carrying out diplomatic tasks and taking on a public role.

He pushed for modernization in a country where Internet access is available only to the elite and satellite dishes are banned. He is the patron of the Syrian Computer Society — a quasi-government organization that trains ordinary Syrians in computer skills and runs computer labs for the public in villages and urban centers.

Fluent in Arabic, French and English, he has led a campaign against corruption.