However, last week's attack on a Damascus suburb that reportedly killed and wounded more than 3,000 people obliterated the "red line" Obama set just over a year ago against the use of Syria's chemical weapons stocks.
White House spokesman Jay Carney told reporters Monday that Obama was evaluating "a response to the clear use on a mass scale with repugnant results of chemical weapons," adding that "there is very little doubt that the Syrian regime ... used those weapons."
Meanwhile, U.S. Secretary of State John Kerry called the attack "inexcusable" and "undeniable," and said that President Obama "will be making an informed decision about how to respond to this indiscriminate use" of chemical weapons.
According to a senior administration official, President Obama will be presented with final options regarding actions against Syria in the next few days. Options available to Obama range from ordering limited missile strikes to continued diplomatic efforts labeled by critics as a "do-nothing" approach.
Assuming the President will choose a military response, any future action could happen as early as mid-week, though it could be later, the official cautioned.
Factors weighing any response include a desire to implement action before the President leaves for Russia next week, and before the administration has to decide whether to suspend aid to Egypt because of the ongoing political turmoil there.
American officials are consulting with allies to ensure they are supportive of any U.S. response; Marie Harf, a State Department spokeswoman, said any U.S. response would be "a determination on how to respond to a blatant use of chemical weapons, and it's not necessarily to change the entire situation on the ground in Syria."
"They have to be careful to do this in concert with our allies," Democratic Rep. Adam Schiff of California, a member of the House Intelligence Committee, told CNN on Sunday, adding that "I don't think the White House is going to want to risk American lives by sending pilots over Syria, so that really limits our options to cruise strikes and think that's probably where the White House is going to go."
That might be a mistake, said Michael Doran, an analyst at the Brookings Institution's Saban Center for Middle East Policy. A U.S. strike "can't just be one and done," but should be part of a plan to remove al-Assad, he told CNN's "Anderson Cooper 360."
"The president has been very reluctant to get involved. Public opinion has been against it. There's not a lot of support on the Hill," Doran said. "And yet, here we are again. Time and time again, we get dragged further and further in." The result could be "a Vietnam-type problem, where we kind of back our way into this, if we don't come up with a plan about how to win."
The Obama administration is expected to declassify the intelligence assessment backing up its assertion that the Syrian regime was responsible for last week's chemical weapons attack, another senior administration official said. The declassification would happen before any U.S. military action would take place.
Earlier Monday, a White House official ruled out sending ground troops to Syria or implementing a no-fly zone to blunt al-Assad's aerial superiority over rebels fighting to oust his regime. The official insisted that all other options were under consideration by Obama but put no time frame on a decision.