U.S. Ambassador to Syria Robert Ford testified today that the Obama administration has not uncovered any evidence of the use of chemical weapons in Syria, but he warned that if the Assad regime uses or loses any of its stockpile, "there will be consequences."

"So far we have no evidence to substantiate the reports that chemical weapons were used yesterday," Ford testified during an ongoing hearing at the House Foreign Affairs committee in Washington. "But I want to underline that we are looking very carefully at these reports. We are consulting with partners in the region and in the international community."

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Ford said officials in the administration "have been very clear" since the beginning of the unrest "about our concern that as the Assad regime's military situation deteriorates … it becomes ever more beleaguered that it might be tempted to use chemical weapons."

He reiterated today President Obama's "very clear" position about the use of chemical weapons in Syria: "If [President Bashar] Assad and those under his command make the mistake of using chemical weapons, or if they fail to meet their obligation to secure them, then there will be consequences, and they will be held accountable."

Ford was recalled from Syria in October 2011 after "credible threats against his personal safety in Syria," according to the State Department.

The precise scope of Syria's stockpile is unclear but, according to the International Institute for Strategic Studies, it has the biggest reserve of chemical weapons in the Middle East, and is thought to have the fourth-largest arsenal on the planet.

Rep. Ed Royce, the chairman of the House Foreign Affairs committee, called on the United States to "organize and empower," including arming, the Free Syrian Army.

"We have let them down, and let down our strategic interests." Royce, R-Calif., said of the Syrian opposition. "Everything should be considered, but the U.S. could have the greatest impact through training, intelligence and logistics."

House Intelligence committee Chairman Mike Rogers Tuesday told CNN: "I have a high probability to believe that chemical weapons were used. … We need that final verification, but given everything we know over the last year and a half, I would come to the conclusion that they are either positioned for use, and ready to do that, or in fact have been used."

Sens. John McCain, R-Ariz., and Lindsay Graham, R-S.C., who have also pressed the administration to become more engaged in Syria, wrote a joint statement Tuesday that if the purported chemical weapon attacks are verified, President Obama is compelled to respond.

"If today's reports are substantiated, the president's red line has been crossed," the duo wrote, "and we would urge him to take immediate action to impose the consequences he has promised."