A renewed police assault on the key Syrian city of Hama this week has exposed deep cracks in the government of President Bashar al-Assad, according to U.S. officials who say the regime is struggling to contain protests in multiple cities while simultaneously grappling with a rapid fall-off in allies, resources and cash.

After abandoning Hama for nearly three weeks, security forces made a hasty return to the country’s fourth-largest city early Monday to clamp down on protests that were drawing the largest crowds seen since the start of the uprising nearly four months ago. But while opposition leaders decried yet another round of arrests and shootings, U.S. officials said the events underscored a growing disarray within the Syrian government, which just weeks earlier had been forced to withdraw troops from Hama and other cities to deal with unrest in towns along the Syrian border with Turkey.

At the same time, the brief window of relative freedom in Hama — capped by raucous demonstrations last Friday that drew an estimated 200,000 people — appears to have both emboldened the protest movement and hardened opposition to any political settlement that would permit Assad to remain in power, U.S. intelligence analysts and diplomats said in interviews.

One senior Obama administration official described the events in Hama as a possible turning point in the uprising, as the government is increasingly challenged to control the swelling throngs of demonstrators in multiple regions of the country. In Hama, a provincial capital with a population of 700,000, the departure of security forces three weeks ago kicked off a series of jubilant, yet largely peaceful, celebrations evocative of Cairo’s Tahrir Square following the ouster of President Hosni Mubarak, said the official, who closely tracks intelligence from Syria.

“Over the course of three weeks, the protests had taken on the atmosphere of a fiesta,” said the official, who like several others interviewed for this article spoke on the condition of anonymity to discuss sensitive intelligence reports. As the crowds grew, the Assad regime “clearly felt they could not allow it,” the official said.

Security forces roared back into Hama on Monday, arresting scores of protesters and firing at others. An opposition spokesman said Wednesday that more than a dozen demonstrators had died in clashes with police.

The renewed violence came two weeks after Assad pledged in a speech to implement political reforms in a concession to an opposition movement that has spurred the gravest political crisis since the Assad family took power four decades ago. Although Assad has called for national reconciliation talks beginning this Sunday, several opposition leaders have said they will boycott the negotiations because of ongoing violence by government forces.

Even before the Hama incursion, U.S. analysts were documenting a steady weakening of the Assad government as some of its core supporters — the alliance of business, religious and tribal leaders that has kept the Assad family in power since 1971 — have soured on the president and his brutal tactics.

One U.S. intelligence official described a “silent majority” of Syrians — including Sunni businessmen and ordinary citizens who have not participated in protests — that is now deeply opposed to Assad and willing to support almost any credible alternative that would restore stability.

“The support base is eroding, and particularly among the business elite,” said the official, who insisted on anonymity in discussing intelligence assessments. “These guys carry a lot of weight, and until now they have benefited from the regime. Now they’re looking for an alternative, and Assad is not part of the solution.”

The Syrian economy has weakened dramatically since the start of the unrest, as foreign tourism dollars have vanished and trade with neighboring countries has dried up. Meanwhile, Western countries have tightened economic sanctions against Syria, and even key allies and trading partners such as Turkey have sought to distance themselves from Syria’s government.

Assad, who until recently appeared confident in his ability to suppress the protest movement, now appears more vulnerable than at any point since the start of the unrest in March, U.S. diplomats and analysts said. At the same time, he has shown no inclination to step down, and there are no clear signs that his downfall is imminent, the officials said.

Some foreign intelligence agencies have said that Assad is determined to cling to power at all costs, with the backing of allies from the country’s Alawite minority, who dominate the country’s political and military establishment.

“The regime is still intact. The military is still intact, and so is the security apparatus,” said a senior Middle Eastern intelligence official who long has monitored Syria’s internal politics. “We believe that the regime has decided to continue with the bloody conflict.”

Staff researcher Julie Tate contributed to this report.