The nation’s leading pro-Israel lobbying group will not support new legislation that would cut off U.S. aid to the Palestinians, according to multiple sources tracking the debate.

The American Israel Public Affairs Committee (AIPAC), the country’s top pro-Israel outfit, is not supporting new legislation by Sen. Rand Paul (R., Ky.) that would cut off aid to the Palestinian government following its decision to form a unity government with the terror group Hamas.

Paul brought his Stand with Israel Act to the Senate floor this afternoon to ask for a unanimous consent vote aimed at expediting action on the measure, according to sources tracking the bill.

While the legislation is expected to garner widespread backing in Congress, AIPAC is quietly expressing reservations about it, according to those familiar with the group’s position.

"We are not supporting the Paul bill," said one AIPAC insider. "We believe the law currently on the books is strong and ensures that aid is contingent on key conditions that help maintain America's influence, keep Israel secure, and advance the peace process."

"I want to be very clear, AIPAC supports a cut off of aid to any Palestinian government that includes an unreformed Hamas, and this is what is provided for in current law," the AIPAC insider said.

Paul's team argues that U.S. law, as currently written, is not strong enough and could be exploited by the Obama administration in order to continue giving aid to the P.A.

"Current law in fact is not strong enough to deal with the current situation, that's why Sen. Paul introduced this bill in the first place," said Doug Stafford, a senior aide to Paul. "And even if it were, does anyone really trust the Obama administration not to take advantage of the waivers?"

"Senator Paul's legislation is stronger, clearer and less open to the interpretation of the Obama administration than current law, and it should be passed immediately," Stafford said. "The fact that AIPAC does not want to support Sen. Paul's Stand With Israel Act to strengthen current law to further protect Israel is disappointing."

Rep. Ileana Ros-Lehtinen (R., Fla.) expressed similar concerns to the Washington Free Beacon earlier this week in an interview.

"I’m very nervous that they’re funding the PA now with this unity government," said Ros-Lehtinen, who explained that it is likely the administration will issue "any kind of qualifier … in order to justify them continuing to send money down this hole."

The Zionist Organization of America (ZOA) has expressed support for Paul's bill.

AIPAC’s public moves on key pro-Israel issues have come under intense scrutiny lately, following its decision earlier this year to bow out of the fight to level new economic sanctions on Iran.

Congressional insiders and pro-Israel activists criticized the group’s decision to quietly bail from the battle for new sanctions, which had been one of AIPAC’s chief priorities.

The group came under scrutiny and criticism earlier this year when it bailed on support for new Iran sanctions, which has been one of AIPAC’s core legislative issues.

During that debate, AIPAC refused to publicly explain why it was abandoning one of its core legislative causes, eliciting frustration from those who had been trying to work with the group.

With battle lines being drawn over Paul’s bill, there are already signs that it could gain traction among many House lawmakers who have been outspoken in recent days about their desire to eliminate U.S. aid to the Palestinians.

Paul’s’ bill aims to strengthen current U.S. law governing aid to the Palestinian Authority (P.A.).

The bill will essentially cut off all U.S. aid to the Palestinians until the president certifies on a yearly basis that the P.A. has publicly recognized Israel as a Jewish state, renounced terrorism, purged terrorists from all areas of the government, ended its funding for anti-Israel and anti-American propaganda, and publicly vowed not to start war with Israel.

The P.A. would have five weeks to comply with the bill before U.S. aid dries up.

Meanwhile, Sens. Marco Rubio (R., Fla.) and Mark Kirk (R., Ill.) wrote to Secretary of State John Kerry on Thursday to ask that he "publicly state that there will be an immediate cut-off" in aid if the new Palestinian unity government fails to renounce terrorism and recognize Israel.

"If Hamas comes to have a role in governance, there must be public acknowledgment of the Jewish state of Israel’s right to exist as well as acceptance of all previous agreements the Palestinians have made with Israel, the United States, and the international community," the senators wrote to Kerry.

"The law also requires that demonstrable progress be made toward dismantling of Hamas’ terrorist infrastructure and purging of individuals with ties to terrorism. Moreover, Hamas would need to halt its anti-American and anti-Israel incitement." the letter said.

"The bar is high because the stakes are high and we must make sure to stand firmly by what we have said," the senators added. "Failing to do so will diminish the credibility of the United States."