SANA, Yemen — President Ali Abdullah Saleh, increasingly isolated amid defections and resignations, clung to power yesterday, at one point indicating he would accept an opposition deal for his early departure — proposed weeks ago — to head off the country’s deepening crisis.

But the opposition said it was too late: They said the proposal to create a plan this year for his early exit from power before 2013 was no longer sufficient and that only his immediate departure would appease the rising tide of protesters.

“He has one option and it is to leave now, right now, without delaying, without conditions,’’ said Mohammed Qahtan of the Joint Meetings Parties, a coalition of opposition parties.

Throughout much of the day yesterday, spokesmen for the government and opposition groups traded barbs, and there were conflicting reports about the nature of the proposal that Saleh had endorsed.

Qahtan called the president a liar and said that the opposition coalition had not been in communication with Saleh since dozens of demonstrators were killed by pro-Saleh forces on Friday.

Saleh, too, struck a defiant tone in a short, nationally televised address yesterday before the country’s National Defense Council. He told military officers still loyal to him that “the winds won’t shake you’’ and warned against a coup.

A government official, who spoke anonymously because he was not authorized to brief reporters, said yesterday that the details of Saleh’s proposal were not yet clear and were “still in the works.’’

The opposition plan, initially proposed by the formal opposition parties earlier this month but rejected by street protesters, urged Saleh to complete arrangements by the end of the year for his early departure. But since then, the opposition parties have backed away from the offer, joining with street demonstrators who want Saleh to quit now.

The United States again expressed concern yesterday that a power vacuum in Yemen could provide an opening for terrorist groups, including Al Qaeda’s local affiliate, called Al Qaeda in the Arabian Peninsula, which since 2009 has mounted multiple terrorist plots against the United States.

“We are obviously concerned about the instability in Yemen,’’ Defense Secretary Robert M. Gates, traveling in Russia, said yesterday. “We consider Al Qaeda in the Arabian Peninsula, which is largely located in Yemen, to perhaps be the most dangerous of all of the franchises of Al Qaeda right now.’’

Saleh appeared willing yesterday to entertain an earlier departure after a wave of high-level officials, including a senior commander, Major General Ali Mohsin al-Ahmar, abandoned him and threw their support behind protesters calling for his ouster. Previously Saleh had offered only to leave by 2013.

The latest of the departures came yesterday when Abdel-Malik Mansour, Yemen’s representative to the Arab League, told Al Arabiya television he had thrown his support behind the protesters. Abdul-Rahman al-Iryani, the minister of water and environment, who was dismissed with the rest of the Cabinet on Sunday, also said he was joining “the revolutionaries.’’

The defection of Ahmar, who commands forces in the country’s northwest, was seen by many in Yemen as a turning point, and a possible sign that government leaders could be negotiating an exit for the president. But the defense minister, Brigadier General Muhammad Nasir Ahmad Ali, later said on television that the armed forces remained loyal to Saleh.

That suggested the possibility of a dangerous split in the military should Saleh, who dismissed his Cabinet late Sunday in the face of escalating opposition, decide to fight to preserve his 32-year rule.

© Copyright 2011 Globe Newspaper Company.