The Obama administration is stepping up pressure on Egypt’s military rulers in advance of parliamentary elections scheduled for Monday, urging faster democratic reforms and curbs on security forces, who are blamed for dozens of deaths in five days of massive street protests.

The private messages to Egyptian leaders come amid new fears that the unrest is undermining prospects for a peaceful transfer to democratic rule in the world’s largest Arab country. White House officials are urging Egyptians to allow the elections to proceed, while acknowledging that worsening violence could make voting impossible.

“Our goal would be for voting to go forward, because a delay would send the wrong message,” said a senior administration official, speaking on the condition of anonymity to discuss internal policy deliberations.

The worries about spiraling violence in Egypt came as U.S. officials struggled to respond to rapidly evolving events elsewhere in the Middle East. On Wednesday, the White House hailed an apparent decision by Yemeni President Ali Abdullah Saleh to cede control of the country to his vice president after 1o months of unrest, while also coordinating with allies on ways to pressure Syrian strongman Bashar al-Assad to step down.

The day also witnessed the formal unveiling of an inquiry into allegations of torture and police brutality against protesters in the tiny Persian Gulf kingdom of Bahrain, a U.S. ally and host to the Navy’s 5th Fleet. The report prompted U.S. officials to defend recent decisions to supply advanced weapons to Bahrain’s government, a move intended as a hedge against future aggression from yet another Middle Eastern trouble spot, Iran.

But it was the prospect of deepening chaos in Egypt that pushed the administration into crisis mode. U.S. officials have viewed the five days of protests in central Cairo with increasing alarm, as they worried about a disruption in the election timeline and the rapidly eroding popular support for an interim military government that until recently appeared to be the guarantor of peaceful transition to democracy.

Administration in a bind

Despite perceived stumbles in the months since the revolution this winter — including a controversial effort to shield the military and its budget from interference from future Egyptian governments — Egypt’s military has maintained close ties with the United States and is regarded by Western governments as a bulwark of stability in one of the world’s most troubled regions. Notably, its generals have continued a tradition of cooperating with Israel on security issues affecting their shared border.

Now, with tens of thousands of protesters in Tahrir Square chanting slogans against the military, the Obama administration finds itself confronting the same dilemma it faced 10 months ago: how to respond to protesters’ demands for democracy while preserving ties with leaders who have reliably protected U.S. interests in the region.

The administration’s initially mild response to the latest violent flare-up drew criticism from members of Congress as well as protesters in Tahrir Square. White House spokesman Jay Carney on Monday lamented the “tragic loss of life” in weekend protests and urged “restraint on all sides.”

The tone toughened somewhat Tuesday, with the State Department explicitly blaming Egypt’s military for the deaths in Cairo. On Wednesday, State Department spokesman Mark C. Toner used similar phrasing in urging the military rulers to show more restraint.

“They did use excessive force against protesters,” Toner said. “We’ve made that very clear in our public, as I’m saying right now, but also in our private conversations with them.”

The private messages have been relayed through a variety of channels, including the U.S. Embassy in Cairo and senior Middle East diplomats at the State Department, an administration official said. Neither President Obama nor Secretary of State Hillary Rodham Clinton have weighed in directly, the official said.

“The message has been pretty consistent,” said the official, who was familiar with the exchanges. “We are underscoring that the [military leadership] needs to respect universal rights of people to express themselves, and they need to ensure that free and fair elections proceed expeditiously.”

Steven A. Cook, a Middle East scholar at the Council on Foreign Relations, said, “What they [the White House] wanted was the military to provide a bridge, a stable bridge, to some sort of new political formula that would bring Egyptians prosperity and a more open, accountable, just political order.”

Instead, Cook said, the White House is now confronted with “the ‘who comes next’ question, and that fear of just general chaos and instability” in Egypt.

‘Who’s left to fill the void’

Indeed, the new crisis finds the administration with even fewer appealing options and less influence than it had 10 months ago, some Middle East experts say. After the departure of Egyptian President Hosni Mubarak in February, the default choice for national caretaker government was the Egyptian army, an institution that enjoyed popularity at home and the respect of governments around the world.

But with central Cairo now paralyzed by demonstrators calling for the ouster of the ruling military council, it is less certain which group will emerge from the chaos to guide Egypt through the difficult months to come, said David Schenker, who was a Middle East adviser to the Pentagon during the George W. Bush administration.

“What happens if the military is routed? Who’s left to fill the void?” said Schenker, a Middle East scholar at the Washington Institute for Near East Policy.

Although disappointed with the military’s anti-democratic policies, he said, the White House has “vacillated on who its allies in Egypt really are.”

Despite calls from some members of Congress, the White House has not threatened to cut roughly $1 billion in annual aid to Egypt’s military, a sum that represents a large portion of its annual budget.

Clinton has warned that the administration would veto any efforts by Congress to attach conditions to U.S. aid to Egypt.