As the White House waits for more evidence to determine whether or not Syrian president Bashar al-Assad crossed what President Obama has called his “red line” and last month used chemical weapons in his campaign against his country’s rebels, Syrian fighters from the ground are reporting a new chemical weapons attack in south Damascus.

On Thursday, the Syrian Support Group (SSG), a U.S.-based advocacy organization that has pressed Obama to provide the Syrian opposition with advanced weapons, issued a report that said two chemical weapons attacks were conducted on April 25 in the southern part of Daraya, a suburb of Damascus. One doctor working from the Daraya medical center said 75 victims were treated for symptoms including “muscle spasms, bronchial spasms, headaches, dizziness, vomiting, and miosis” following a 1 a.m. rocket strike. Another 25 victims were sent to the medical center complaining of similar symptoms when a second attack hit the area at 7 a.m. local time, according to the SSG and a statement from the local coordinating council of Dariya, a media group affiliated with the Syrian opposition.

The Daily Beast was unable to confirm the report. But the allegation comes after the White House acknowledged today that the U.S. intelligence community had “varying degrees of confidence” that sarin gas was used on a small scale in attacks in Syria. U.S. defense and intelligence officials say the alleged attacks included attacks on March 19 in Damascus and Aleppo.

The SSG, one of the first to report on the March 19 attacks, said victims of Thursday’s chemical strike exhibited symptoms similar to those from the March 19 attacks, in which rebel groups claimed the regime used weapons armed with echothiophate—an organophosphate similar to sarin.

If the rebel report is true, it is a nightmare scenario for the Obama administration. Democrats and Republicans on Thursday warned that the administration’s cautious approach to confirming evidence of a chemical attack may end up emboldening Assad. In the past year, Assad has used SCUD missiles and fixed-wing aircraft to attack civilian areas, an escalation from his initial response to the Syrian uprising in 2011.

“Until now our response on Syria has been so late on almost everything, we are not able to shape the environment,” said Andrew Tabler, a Syria expert and senior fellow at the Washington Institute for Near East Policy. “If this report is accurate and Assad has used chemical weapons again today, then our policy to deter him is not working, it’s clear he is escalating his attacks and is becoming more emboldened.”

On Thursday, the White House told reporters and members of Congress that it would wait for more facts before determining definitively that Assad had used chemical weapons. Obama has said the use of chemical weapons would be a “game changer,” along with transferring chemical weapons to other states or groups.

The decision to gather further details is based in part on the nature of the intelligence collected by U.S. allies. Two U.S. officials who work on Syria policy tell The Daily Beast that assessments from three allied services—France, Israel and the United Kingdom—are not ironclad and leave room for interpretation. “The French and the British assessment are squishy,” one of these officials said. The Israeli assessment is largely based on photo analysis, another official said, pointing out that photographic analysis is not as solid as other kinds of evidence.

Another U.S. intelligence official, however, disputed this view. “The British have soil samples,” this official said. “When you have the Israelis, the French, the British and even some of our Arab friends saying this happened, I don’t know what the White House is really waiting for.”

The question of whether chemical weapons were used in Syria recently has enormous implications for U.S. policy. To date, Obama has committed several hundred million dollars in direct non-lethal aid to elements of Syria’s opposition. He has vetoed a plan however to provide those elements with more advanced weapons supported late last year by former CIA director David Petraeus and former secretary of state, Hillary Clinton.

On Thursday, Sen. Dianne Feinstein, the Democratic chairwoman of the Senate Select Committee on Intelligence, issued a statement saying “red lines have been crossed.” She also joined several Republicans, including Sen. John McCain, in supporting an escalation of U.S. response to the Syrian conflict. Feinstein’s counterpart in the House, Rep. Mike Rogers, said, “President Obama correctly said that Syria’s use of chemical weapons would be a red line for the United States. Now that we have confirmed their use, the question is what is our plan for transition to a post-Assad Syria?”

One possible response for the White House would be to provide elements of the Syrian opposition with the anti-aircraft and anti-tank weapons it has requested for nearly a year.

But it appears that, for now at least, Obama’s cabinet is divided on whether to further arm the Syrian opposition. Last week, Secretary of State John Kerry told Congress that the United States was working with other actors in the Middle East to funnel guns to members of the opposition. The same day he said that however, Gen. Martin Dempsey, the chairman of the joint chiefs of staff, said he did not have confidence the United States could identify the right people in the Syrian opposition. One element of the opposition is believed to be closely tied to al Qaeda under the banner of a group called al Nusra. In December the State Department designated al Nusra as a foreign terrorist organization.