Saleh has said that there will be "no inheritance" of his presidency, but there's little to prevent his son, Ahmed, or any other member of the family (many of whom are senior officers in the military) from campaigning on their own. In a free election, the unpopular Ahmed would almost certainly lose, but his father could engineer an electoral victory.

Another contender is Brigadier General Ali Mohsen al Ahmar, the leading commander of the Yemen Armed Forces and, by most accounts, the second most powerful man in the country. Last year, he declared he would not tolerate Ahmed Saleh becoming president, perhaps signalling that the general is waiting for his own turn. His chances of a legitimate victory are also poor. Military campaigns against a rebellion in the north and a crackdown on southern dissidents have alienated al Ahmar from much of the public. If he does not like the results, though, a military coup is always a possibility.

In the event of a free election, the strongest candidate would probably come from the opposition Joint Meeting Parties (JMP), a coalition of convenience for a number of parties with interests ranging from moderate socialist secession in the formerly independent south to the legislation of puritanical religious practice. The strongest of these parties is Islah, itself a conglomeration of tribal partisan and Wahabbists, an ultra-conservative Islamic sect dominant in Saudi Arabia. Their candidate would probably be a moderate, such as Hamid al Ahmar, a party official and leader of the Hashid Tribal Federation, Yemen's largest tribe, which also happens to include Saleh and General al Ahmar. But it's difficult to know how Islah would govern. It's unclear how much the party is dominated by its religious element, which includes Sheikh Abdul Majid al Zindani, known in Yemen as a henna-bearded popular icon but known to the U.S. as a Specially Designated Global Terrorist associated with financing al Qaeda and possibly recruiting for the attack on the USS Cole. Last October, Islah's religious wing blocked a parliamentary measure that would have codified a legal age for marriage, provoking a fist fight on the Parliament floor.

Much like in Egypt, the popular opposition in Yemen has been so effectively fragmented and marginalized by the government that no one group is well enough organized to fill the void that would open if the three decades of centralized rule were to collapse. Yemen has two years to prepare for a peaceful transition of power, in which parties will jockey for power in the tinderbox of Yemeni politics. Groups that refuse to work within the transition - the Houthi rebels in the north, the secessionist movement in the south, al Qaeda in the Arabian Peninsula in the rural interior, authoritarian military elements - could touch off violence that would force the parties to factionalize. Civil war is never off the table in Yemen.