House lawmakers are deeply divided over proposals to arm rebel groups in Syria, amid unconfirmed reports that President Bashar Assad has used chemical weapons against opposition forces.

At a hearing Wednesday, lawmakers pushed back on legislation from the top Democrat on the House Foreign Affairs panel, Rep. Eliot Engel (D-N.Y.), that would provide $150 million in military assistance, including weapons, to forces looking to topple Assad’s government.

{mosads}Rep. Ileana Ros-Lehtinen (R-Fla.), the panel’s former chairwoman, warned that the arms could fall into the hands of groups hostile to the U.S. or Western interests.

“While I respect the opinion of my colleagues, I sincerely do not believe that it is time for the U.S. to arm the rebels,” she said.

“Too many questions remain about who the rebels are and with whom they will swear allegiance. The unknown can be dangerous, and the vetting of the opposition is not enough when it comes to providing lethal aid that could be used against our allies, such as Israel, or the United States in a post-Assad era,” Ros-Lehtinen said.

Supporters of the measure, though, argue that the U.S. has remained on the sidelines of the conflict for far too long.

“For two bloody years, U.S. policy has been adrift,” said House Foreign Affairs Committee Chairman Ed Royce (R-Calif.). “We need to help better organize and empower the Syrian opposition. … Everything should be considered, but the U.S. could have the greatest impact through training, intelligence and logistics.”

Rep. Ted Deutch (D-Fla.), who stood in for Engel while he travels to Israel with the president, cautioned that safeguards should be taken to ensure that opposition forces friendly to the U.S., and not Islamist groups, received arms.

“It is our responsibility to determine whether this can be done in a way that ensures U.S. arms will not fall into the hands of terrorist organizations,” he said. “This is an important conversation for us to have. And we should have it right now.”

Many lawmakers are pressing the Obama administration for greater involvement amid reports that well-armed Islamist groups are gaining the upper hand against more pro-Western forces. But Wednesday’s hearing highlighted uncertainty in Congress over providing military aid.

Sens. John McCain (R-Ariz.) and Lindsey Graham (R-S.C.) have long called for arming the rebels, and Senate Armed Services Committee Chairman Carl Levin (D-Mich.) said Monday that he favored U.S. air strikes against Syria’s air defense systems.

On Tuesday, Sens. Bob Casey Jr. (D-Pa.) and Marco Rubio (R-Fla.) unveiled legislation calling for more aid to vetted rebel groups and increased sanctions against banks doing business with the Assad government. And House Intelligence Committee Chairman Mike Rogers (R-Mich.) said Wednesday it is “time to act” against Syria’s chemical weapons stockpile.

“The United States has lost the faith of the opposition. They’ve at one point turned down a meeting with the secretary of State of the United States, they’re so fed up. And our allies in the region are getting very nervous about us,” Rogers told CBS. “If we’re ever going to have a diplomatic solution where this regime doesn’t get to the point where it uses mass quantities of chemical weapons, we’ve got to rebuild our credibility and one way to do that is to remove their capability to use chemical weapons on civilians.”

The U.S. ambassador to Syria, Robert Ford, testified Wednesday that the State Department was “very skeptical” of Syrian government and Russian claims that the rebels used chemical weapons on Tuesday.

“So far, we have no evidence to substantiate reports that chemical weapons were used yesterday,” he said. “The president has been very clear in saying that if 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.”

He reiterated that the administration’s preference was to help negotiate a peaceful political transition, but he did not definitively rule out arming the rebels, as France and Britain now call for doing.

The leaders of the State and Defense departments urged Obama to take such action last year but were overruled by the White House amid concerns that weapons could end up in the hands of Islamists. 

“With respect to direct military assistance, our policy now is to not provide military assistance to [the rebels],” Ford said. “We do regularly review this. Let me be clear about that.”