Louay Safi, spokesperson for the Syrian opposition, addresses the media after a meeting at the Geneva Conference on Syria at the United Nations European headquarters in Geneva on Saturday. (Denis Balibouse/REUTERS)

U.N.-sponsored peace talks for Syria ended at an impasse Saturday with few signs that the parties would resume their negotiations, as the Obama administration lashed out in frustration at Russia, accusing it of prolonging the conflict.

“They can’t have it both ways,” a senior Obama administration official said of Russia, which is Bashar al-Assad’s principal international backer but also supported the U.S. idea of inviting both sides to the negotiations. Russia can’t say it wants that peaceful approach and a “happy Olympics” while it is also “part and parcel of supporting this regime as it kills people in the most brutal way,” the official said.

Seizing on Russia’s role as host of the Winter Olympics in Sochi, the official said that country was being disingenuous in its approach to the conflict in Syria, where three years of violence has claimed 140,000 lives.

The official spoke on the condition of anonymity to describe the agenda for an unusual meeting Saturday in California between President Obama and Jordan’s King Abdullah II, at which the two leaders discussed the failing international efforts to broker peace and ease desperate conditions in Syria.

Abdullah requested the meeting, partly to seek additional U.S. help for coping with an overwhelming flow of refugees. His small, Western-oriented nation is deeply uneasy about the near collapse of Syria and the spread of Islamic militancy in the vacuum.

“It’s not good for Syria that we come back for another round and fall in the same trap that we have been struggling with this week and most of the first round,” U.N. envoy Lakhdar Brahimi said in Geneva, where the acrimonious talks ended on a somber note.

Brahimi apologized to the Syrian people for the lack of progress after two sessions of face-to-face meetings between Assad’s representatives and members of the opposition in exile. Brahimi urged both sides to consider whether they were ready and willing to go on and, for the first time, lay blame for the failure at the feet of the Syrian government.

The opposition, backed by the United States and numerous other nations, insists that the talks are premised on naming a power-sharing government to replace Assad. Assad’s envoys scoffed at that and said they showed up to raise awareness of what the Syrian regime’s leader calls a terrorist threat feeding on the chaos and spilling over into other countries in the Middle East.

The talks were a risk for Syria’s moderate opposition, which feared losing what little influence and credibility it carries among front-line fighters. Brahimi was unable to get the regime to agree to even a small package of humanitarian concessions, a step meant to help the opposition show that the talks could deliver tangible help for the besieged.

A humanitarian cease-fire in Homs has been presented as a bright spot, although that had been under discussion for months. Brahimi said the modest progress in the city had given the Syrian people hope that the process could bear fruit.

“I apologize to them that, on these two rounds, we haven’t helped them very much,” he said.

Syria’s ambassador to the United Nations, Bashar Jaafari, said the government had accepted the agenda but had issues with the opposition’s unrealistic interpretation of it. The opposition said in a statement that its representatives had come to Geneva to make peace but had found at the table not “a negotiating partner, but puppets on strings pulled by Damascus.”

The Syrian National Coalition, an umbrella opposition group, announced Saturday that its leader, Ahmed Jarba, had traveled to the front lines while the talks were going on. Jarba, who is based mostly in Turkey, visited locations around Idlib Governorate, his office said.

“We are connected with this land and will not compromise on the values of this revolution,” Jarba’s office quoted him as saying. “We will get rid of this corrupt and criminal family who has been ruling this country for decades.”

No Plan B

With no date set for a resumption of talks, it seems likely the violence will only continue to intensify. Western diplomats have acknowledged that they have no Plan B for what to do next should negotiations fail.

The Geneva talks represent the only strategy Obama has advanced to try to end the war, and both Obama and Secretary of State John F. Kerry have acknowledged in recent days that it isn’t working. Obama reiterated last week that he has ruled out direct military action, but his administration is seeking other ways to coerce better humanitarian access at the least. Russia is blocking any discussion of serious consequences for Assad at the United Nations, adding to U.S. frustration this week.

The official said the United States hopes to push forward with a U.N. Security Council resolution providing for greater humanitarian relief in Syria. Jordan has started a two-year term on the council, of which Russia is a permanent, veto-holding member.

“As long as they remain wedded to the status quo, this is going to be a very difficult problem to resolve,” the official said of the Russians. “They have a pretty sorry record,” having vetoed three previous attempts to hold Assad accountable at the Security Council, the official said. “I don’t think any of us have any expectation that they are going to turn on a dime.”

‘Not a partner for peace’

Sen. John McCain (R-Ariz.), a frequent critic of the White House policy on Syria, said it is no surprise that the second round of talks in Switzerland came to naught. While the discussions were underway, the killing in Syria actually accelerated, he said.

“The entire strategy for success at Geneva now relies on Russia putting pressure on the Syrian government to engage in a serious and constructive way,” McCain said. “Yet Russia has recently prevented the passage of a much-needed U.N. resolution on bringing aid to desperate Syrian civilians” while continuing to arm Assad.

“The Russian government is simply not a partner for peace in Syria and cannot be relied on to help secure a successful outcome,” McCain said.

During the talks, the Assad government has been accused of stepping up attacks on the ground in Syria, conducting devastating aerial campaigns against the northern city of Aleppo and rebel-held areas near the Lebanese border.

According to the opposition Syrian Observatory for Human Rights, more than 3,400 people have been killed since the first round of talks began in Geneva on Jan. 22, the fastest pace of deaths during the war so far.

After a last-ditch attempt Saturday to find a way out of the diplomatic impasse, Brahimi said the Syrian government had rejected his proposed agenda for a new round of talks, leaving their prospects unclear.

“I hope that this time of reflection will lead the government side, in particular, to reassure the other side” that it is committed to negotiations that will lead to a transition of power, he said.

Amid the stalemate, the United Nations has held trilateral talks with representatives from the United States and Russia in an attempt to kick-start negotiations. Brahimi said he hoped U.N. Secretary General Ban Ki-moon, Kerry and Russian Foreign Minister Sergei Lavrov would meet soon to find a way to proceed.

Morris reported from Beirut. Zachary A. Goldfarb in Rancho Mirage, Calif., and Liz Sly in Gaziantep, Turkey, contributed to this report.