After weeks of collecting intelligence on Syria and watching the attacks by the forces loyal to Bashar al-Assad, the U.S. sees "no fracturing" of the Syrian regime and assesses al-Assad could remain in power for some time to come if the situation does not change, according to a senior U.S. official.

This the basic conclusion of top officials closely watching Syria, the official said. Unless something changes in the next several days, this will also be the message delivered to the Senate Armed Services Committee next week by Defense Secretary Leon Panetta and Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff. The hearing, called for Wednesday, is the first public hearing in which both men will be publicly questioned by Congress on the Syrian crisis.

Sen. John McCain, the senior Republican on the committee, has already called for arming rebel forces, something the defense secretary expects to be asked about, according to the official. The issue of U.S. military planning for options in Syria is also expected to arise, but officials say the secretary and the general may not be able to offer many specifics in an open session before the public.

Instead, they are likely to talk more about the current situation in Syria and how the U.S. views the al-Assad regime.

"The assumption is Assad will continue to persevere until he and other regime leaders are sufficiently suppressed," the official said. While there have been a number of defections, it's not yet at the point of tipping al-Assad's grip on power.

As for al-Assad, "He's enjoying tactical survival. He can wait it out. He looks to be dug in" the official said. So far, al-Assad is believed to enjoy unhindered movements and communications. But the hope, he said, is that al-Assad is feeling the "strategic weight and pressure of outside critics."

The official's characterization matches the assessment given to Congress by Director of National Intelligence James Clapper, who told a Senate hearing in mid-February that all signs pointed to al-Assad holding on, including little indication of military desertions.

But the newer assessment, even as world condemnation grows louder, suggests al-Assad's regime is holding up the pressure. Last week at an international meeting on Syria held in Tunisia, Secretary of State Hillary Clinton called on the Syria military to disobey their orders.

"The longer you carry out its campaign of violence, the more it will stain your honor. But if you refuse to take part in attacks on your fellow citizens, your countrymen will hail you as heroes," Clinton said.

Clinton also said there were indications that his supporters are beginning to have doubts.

"We also know from many sources there are people around Assad now who are beginning to hedge their bets. They didn't sign up to slaughter people, and they are looking for ways out. We saw this happen in other settings in the last years. I think it is going to begin happening in Syria," Clinton said while in Tunisia for an international meeting on Syria.

But the latest U.S. assessment does not indicate that is happening yet.

The longer the conflict in Syria goes on and the regime holds out, the greater the chance for the country to descend into full-scale civil war, two senior State Department officials said Thursday.

Jeffrey Feltman, assistant secretary of state for Near East affairs, said the United States is working with its allies to reach a "tipping point" whereby the regime falls, and a new government representative of all Syrian society takes over.

Time is of the essence, he said.

"The demise of the Assad regime is inevitable," Feltman told the Senate Foreign Relations Committee. "It's important that the tipping point for the regime be reached quickly because the longer the regime assaults the Syrian people, the greater the chances of all-out war and a failed state."

But the opposition is not as organized as it was in Libya and is "divided" and "fractious" the officials said.

"The opposition leadership recognizes those dangers," Feltman said, noting the importance of beginning a transition in Syria soon. "The longer this goes on, the deeper the sectarian divisions, the higher the risks of long-term sectarian conflict, the higher the risk of extremism."

The leading political organization, the Syrian National Council, and the rebel Free Syrian Army have organizational issues of their own.

"The two organizations are separate. There is not a hierarchy between them," Ambassador Robert Ford, who recently returned to Washington following the closure of the U.S. embassy, told the panel. "They are not organically linked," he said, but added the two groups do talk and coordinate at local levels within Syria.

Despite the lack of organization, Ford said there was still a unity of purpose from his perspective. "They want a country where people are treated with dignity, everybody is treated with dignity" he said. "They have a vision of a country ruled by law."

That vision did not sit well with a senator on the committee who attended a classified briefing on Syria earlier in the week. The hour-long session was conducted at the Capitol on Wednesday and was focused on discussing the Syrian opposition, CNN's Ted Barrett reported.

"We heard no words whatsoever about anything other than this being a conflict between one group of people that has been oppressed by another group of people, and their desire to change that equation," Sen. Bob Corker, R-Tennessee, told Ford. "The people fighting, from what I understand, are fighting for, you know, power and government. They're not fighting under the banner of democracy," he said.

"Senator, I'm going to have to respectfully disagree," Ford said.

The United States supports a transition laid out by the Syrian National Council from which a post-Assad leadership would be chosen, Ford said. "The people who are doing the fighting say they are fighting to defend the protest movement," he said. "So there is a link even if you can't say that the fighters themselves claim they're fighting for democracy."