GENEVA - International envoy Kofi Annan believes his six-point peace plan for Syria remains "on track" as the truce monitoring team grows to a sixth of its U.N.-authorized size, an official said Friday.

The assessment came a day after the Obama administration offered a bleaker view that it may be time for the world to acknowledge the cease-fire is not holding in Syria, and other approach might be needed.

Ahmad Fawzi, Annan's spokesman, told a U.N. briefing in Geneva that negotiations are being "conducted under the radar" involving the Syrian government and its opposition to cease all hostilities, and "there are small signs of compliance," despite continuing violations of truce conditions such as heavy weapons in populated areas.

"The Annan plan is on track," Fawzi insisted. "And a crisis that has been going on for more than a year is not going to be resolved in a day or a week."

On Thursday, the White House press secretary, Jay Carney, told reporters that "if the regime's intransigence continues, the international community is going to have to admit defeat."

Most observers and diplomats agree that the Annan plan has done little to stem the bloodshed, but so far other nations that back it have been unwilling to say it is dead. U.S. officials say the plan is failing mainly because of Syrian government violations.

But both Syrian President Bashar Assad's government and the Syrian opposition are blaming each other for flouting the cease-fire.

Annan, the joint U.N.-Arab League envoy, is scheduled to brief the U.N. Security Council on Tuesday by videoconference from Geneva with the latest assessment on implementation of his six-point peace plan.

U.N. truce observers have been touring restive parts of the country where the U.N. estimates 9,000 people have been killed since the revolt began more than a year ago.

The head of the U.N. observers, Norwegian Maj. Gen. Robert Mood, told reporters Thursday in Syria that there is still "a good chance and an opportunity" to break the cycle of violence.

Fawzi said Mood's team will have "around 50" observers on the ground by the end of Friday, and that the United Nations has obtained commitments from nations for 150 of the 300 observers that the U.N. Security Council authorized.

"It's not an advance team any longer," Fawzi said. "The numbers are growing every day."

He also said Mood's truce observers are not being targeted, despite suicide blasts occurring near a hotel where some of them were staying.

But Fawzi acknowledged that "there are days when things are progressing in a satisfactory manner, and there are days where we feel that it's a rough ride." He said, however, that even on days when there is progress "we are horrified by the extent of violence we see on the ground."