The activists who spearheaded Yemen’s populist rebellion threatened on Wednesday to take matters into their own hands if political leaders refuse to abandon President Ali Abdullah Saleh and pave the way for a transition of power.

The ultimatum reflected frustration among the activists at a time when Yemen’s political opposition appears increasingly fragmented by dueling visions of how to remove Saleh from power and create a new political era for this poor but strategic Middle Eastern nation.

Even with the president outside the country, seeking medical treatment for severe injuries, the activists fear that they could lose the gains they have achieved and that Saleh’s regime could continue in his absence. Late Wednesday night, after the government announced that Saleh’s health was improving, celebratory gunfire and fireworks erupted across Sanaa in an apparent show of strength by Saleh’s loyalists.

Other centers of power have emerged in recent weeks, including influential tribal leaders who head militias; defected military leaders; and Saleh’s sons and nephews, who control much of the security forces and, in effect, are shepherding his authority in his absence.

The activists’ threat to install a provisional presidential council was an attempt to bolster the influence of the Yemeni street. They also denounced the opposition political parties that had been negotiating unsuccessfully with Saleh for a handover of power before the Friday attack on the presidential palace that sent the Yemeni leader to Saudi Arabia on Saturday for emergency care.

“We would like to announce that the JMP is part of the regime that we are seeking to remove,” said Tawakkol Karman, a prominent activist leader, referring to the Joint Meeting Parties, a coalition of six opposition groups. “In any new government, if the JMP is part of it, our revolution will continue.”

Many activist leaders think the traditional opposition parties are just as tainted as the president’s supporters. Throughout his 33-year rule, Saleh, one of the Middle East’s master political tacticians, has co-opted his adversaries through a system of patronage, leaving the political opposition weak and divided. Senior opposition leaders have businesses and other sources of wealth that depend on the benefaction of the government.

Two paths to a new Yemen

The activists want a complete overhaul of Yemen’s government, without any remnants of the past; they also want Saleh and his relatives who wield power brought to justice. But the JMP, concerned about insecurity, has pushed for a more gradual transfer of power.

It prefers a proposal by the Gulf Cooperation Council, a group of Yemen’s neighbors led by Saudi Arabia. That plan calls for Saleh to officially hand over authority to his vice president in exchange for immunity from prosecution for himself and his relatives. The vice president would then create a transitional unity government, including members of Saleh’s ruling party, that would govern until elections were held.

Many youth leaders have rejected the GCC proposal, which has deepened their suspicions of the JMP. They think the JMP is aligning with the Yemeni street as a way to gain political power.

“It seems the JMP is looking for power, while the youth are looking to create a new country,” said Adel Arrabyee, a youth leader.

Muhammed Qahtan, a senior JMP leader, dismissed the activists’ demands as unrealistic. He said the way forward is not by creating a shadow transitional presidential council but by persuading Saleh to officially hand over power to Vice President Abed Rabbo Mansour Hadi, the acting head of state, as the GCC proposal calls for.

“Without doubt the youth are upset with us, and if it is up to them, they will want to come up with something new. Our hearts go with their wishes, but politics is the art of what is possible,” Qahtan said. “It’s the nature of youth. They don’t like any middle solutions.”

A ‘political joke’

Ahmed al-Sufi, a spokesman for Saleh, also dismissed the activists’ ultimatum and described the potential creation of a transitional presidential council as a “political joke.”

Qahtan said that the international community, including the United States and European countries, sees the GCC proposal as the best path forward and that “to challenge the international community would be a suicide mission.”

Indeed, the Obama administration on Wednesday urged Yemen’s government to seize the opportunity created by Saleh’s absence. U.S. officials on Tuesday said the president’s injuries were more serious than initially thought and that he may need months to recover. U.S. officials have pressed their views with Hadi, State Department spokesman Mark Toner told reporters Tuesday.

“There is a government that remains in place there, and they need to seize the moment and move forward,” Toner said.

But Hadi’s government is no longer the sole center of power.

Other major players in Yemen include Maj. Gen. Ali Mohsen al-Ahmar, Saleh’s closest ally until he defected in March after the killings of dozens of protesters by snipers loyal to the president.

While Mohsen has largely stayed out of the political fray and out of the public eye, he remains influential. His troops guard Change Square, where tens of thousands of protesters have camped out for months, and they are the most significant military force that could challenge the troops controlled by Saleh’s sons and nephews.

Tribal militias linked to the family of Sadeq al-Ahmar control some areas, including the Hasaba district in northern Sanaa, where the family has residences. The Ahmars have long played a significant role in Yemen and are among the country’s wealthiest citizens. One son, Hamid, a business tycoon, is a top leader in the political opposition who is widely viewed as a potential successor to Saleh.

In the south, Islamist militants linked to al-Qaeda’s Yemen branch have taken advantage of the turmoil. They have gained control of areas in Abyan province, an al-Qaeda stronghold, including the southern city of Zinjibar. But so far, al-Qaeda has not weighed in vocally in the political arena.