Demonstrators burn a photo of Egyptian President Hosni Mubarak's son and heir apparent, Gamal Mubarak, during a protest last year. Photo: Flickr.

Demonstrators pouring into the streets of Cairo and other Egyptian cities today are posing the greatest challenge to President Hosni Mubarak’s authoritarian rule in decades. If they get their way, Mubarak will stand down and allow free and fair elections to take place later this year. And if that happens, Egypt’s favorite parlor game — guessing who will succeed the 82-year-old autocrat — will suddenly get a lot more complex.

As new diplomatic cables released this week by the anti-secrecy organization WikiLeaks show, speculation about who might succeed Mubarak has swirled for years, and will only grow more intense as opposition groups call for him to step down. On Friday, Mubarak ordered his entire cabinet to resign, a move that may further complicate the guessing game, given that several members of Mubarak’s government were seen as possible presidential contenders.

The leading prospect, however, has long been Mubarak’s 47-year-old son, Gamal Mubarak, an international banker and senior official in Mubarak’s ruling National Democratic Party (NDP). As the WikiLeaks cables show, the younger Mubarak emerged as a possible presidential contender as early as 2006, when he began asserting his political influence in the country more aggressively. In a message to Washington that year, U.S. diplomats in Cairo described Gamal Mubarak as “a rising star” who had increased his public profile, partly after a series of government shakeups by his father had sidelined other, more senior figures. And as recently as 2009, a senior NDP official told U.S. diplomats that the Egyptian military would “ensure a smooth transfer of power, even to a civilian,” a reference to Gamal.

American officials at the time cautioned, though, that such a move “remains deeply unpopular on the street.” That simmering resentment among Egyptian citizens and opposition figures is especially apparent today; during the protests roiling Egypt’s major cities, activists called not only for Mubarak to resign for but his son not to succeed him. Some of those groups are instead turning to Mohamed ElBaradei, a former director general of the International Atomic Energy Agency and Nobel Peace Prize winner who returned recently to Egypt to support the protesters, stoking speculation that he might run to replace Mubarak.

As U.S. diplomats noted in February, ElBaradei remains popular among opposition activists. His return to Egypt in February became a rallying point for government critics, and ElBaradei met with several of them at his home in Cairo to plan the formation of a new opposition coalition that would lobby for democratic reforms. As U.S. officials wrote in a cable at the time, ElBaradei’s return to Egypt “seems to have energized opposition political activists and the independent press.”

Other potential presidential candidates, according to the WikiLeaks cables, include Amr Moussa, a senior Egyptian diplomat and secretary-general of the Arab League who was described as a “dark horse” by U.S. officials; Mohamed Tantawy, one of Mubarak’s closest military advisers and Egypt’s minister of defense; and Omar Suleiman, another close adviser to Mubarak and director of Egypt’s intelligence services. Tantawy and Suleiman were seen as especially serious threats to Gamal Mubarak’s presidential ambitions, U.S. officials wrote in a 2007, but their prospects are less clear now that Mubarak has promised to fire his government, of which both Tantawy and Suleiman were members.

Of course, Mubarak’s influence over the succession process is now in serious doubt. And as U.S. diplomats noted in the cables, there appears to be no plan in place for an orderly presidential transition. Mubarak has never named a vice-president and seems to have been counting on his ability to remain in power for several more years. If protesters do somehow force Mubarak’s ouster, the question of who will lead Egypt will inevitably become even more clouded.

“Despite incessant whispered discussions, no one in Egypt has any certainty about who will eventually succeed Mubarak nor under what circumstances,” U.S. officials wrote in a 2009 cable. “Indeed, he seems to be trusting to God and the ubiquitous military and civilian security services to ensure an orderly transition.”