A deal to end Yemen's political crisis neared collapse on Sunday after the country's embattled president refused to personally sign it, leaving a deadlock that threatens to plunge the impoverished Arab nation and key U.S. ally deeper into disorder and bloodshed.

An unraveling of the deal for Ali Abdullah Saleh to step down after nearly three months of protests against his rule would greatly increase the prospects of more bloodshed in a nation long beset by serious conflict and deep poverty and which is home to al-Qaida's most active offshoot.

At least 140 people have been killed in the government's crackdown on the protesters, who have nonetheless grown in number week after week. The violence, which has included sniper attacks, has prompted several top military commanders, ruling party members, diplomats and others to defect to the opposition, largely isolating the president.

Still, Saleh has clung to power, thanks in part to the key backing of Yemen's best trained and equipped military units, which are under the command of one of his sons and other close relatives.

"There will likely be more violence now," said analyst Fares al-Saqqaf. "In the end, we may have foreign intervention to end the chaos and bloodshed," he predicted.

Continued unrest in Yemen risks the stability of a region that is home to important shipping lanes at the southern mouth of the Red Sea. Yemen is also close to the massive oil and gas fields of the Gulf Arab region.

The country has over the years been wracked by rampant corruption, a weak central government, a Shiite rebellion in the north, a secessionist movement in the south and, since early February, the massive protests demanding Saleh's ouster.

Inspired by uprisings in Egypt and Tunisia, the protests pose the most serious threat to Saleh's authoritarian rule. Saleh has sought to cling to power by offering the protesters concessions, pledging not to run again in 2013 elections or allow his son to succeed him. The protesters stood their ground, demanding his immediate resignation and his trial for the killing of protesters and corruption.

A mediation plan put forward by six U.S. allies grouped in the Gulf Cooperation Council, or GCC, looked close to fruition, with the established opposition political parties and Saleh himself agreeing to it. The plan called for Saleh to step down within 30 days and for a national unity government to run the country until elections are held.

The proposals also gave Saleh immunity from prosecution.

The street protesters, who say the opposition parties taking part in the talks do not represent them, rejected the deal and said nothing less than Saleh's immediate resignation would persuade them to halt their massive demonstrations. Still, the Gulf initiative held some promise, but that subsequently vanished when Saleh told a GCC envoy late Saturday that he would send representatives to sign the deal — rather than signing it himself — at a ceremony that had been scheduled for Sunday or Monday in Riyadh, the Saudi capital.

The opposition said it would not sign it unless Saleh did too and the GCC, a loose alliance of oil-rich Gulf Arab nations, said it was indefinitely postponing the ceremony, blaming Saleh's refusal to sign.

"President Saleh, like any dictator, does not want to leave power and is doing everything he can to win time and stay longer in power," said Mohammed al-Sabri, a spokesman for the opposition political parties. "He cannot be trusted."

The GCC nations' foreign ministers met Sunday in Riyadh and said they were sending the council's secretary-general, Abdullatif bin Rashid al-Zayani, back to Yemen to try to salvage the deal.

The council "hopes to remove the obstacles that are still hindering reaching a final agreement between the parties in Yemen," it said in a statement.

The GCC comprises Saudi Arabia, Kuwait, United Arab Emirates, Qatar, Oman and Bahrain.

The Yemeni government said Saudi Arabia's King Abdullah and Saleh discussed the GCC proposals by telephone Sunday but gave no details.

Government officials said Saleh had told al-Zayani of the GCC on Saturday that he intended to ratify the deal after sending a close aide and a senior ruling party official to sign it. The officials, who spoke on condition of anonymity because they were not authorized to speak to the media, said Saleh's ratification would be in his capacity as head of the ruling party and not as president.

The opposition feared Saleh was leaving himself room to stay in power and leaders of the street demonstrations said they planned to step up their protests to force Saleh out.

Tens of thousands of protesters were out Sunday in a number of Yemeni cities, including Aden and Taiz in the south, to demand that he step down.

"We will not pay attention to any mediation or foreign intervention," said protest leader Abdel-Hadi al-Azazi in Sanaa, the capital. "We will continue to march and protest until the uprising's goal is achieved — the ouster of the regime."

Despite gunfire, protesters in Aden pushed their way back into a central square that had been cleared by security forces a day earlier, said Shaher Masaabeen, one of the demonstrators. Medics said two protesters were injured by gunfire.

In the eastern province of Hadramawt, unknown gunmen firing from a moving car killed four soldiers and fled, said a security official who spoke on condition of anonymity because he was not authorized to speak to the media.


Hendawi reported from Cairo.