Updated 7:20 a.m. Friday

A draft resolution being circulated by two moderate Democratic senators would give the government of Syrian President Bashar al-Assad 45 days to sign an international chemical weapons ban or face the threat of "all elements" of U.S. military power.

Sen. Heidi Heitkamp (D-N.D.). (LM Otero/AP).

Sens. Joe Manchin III (D-W.Va.) and Heidi Heitkamp (D-N.D.) are working on the alternative proposal, which would delay the immediate use of military force and compel the Obama administration to build more international and American political support for striking the Assad government, according to Senate aides familiar with the talks.

The resolution would give the Assad government 45 days to sign the chemical weapons ban and require President Obama to present lawmakers with a plan to end the violence in Syria through diplomatic means, according to a draft copy of the resolution obtained by The Post from Senate aides.

Aides cautioned that the final wording of a resolution is still in the works, but provided this proposed language:

“The failure by the government of Bashar al-Assad to sign and comply with the [Chemical Weapons] Convention clearly demonstrates a disregard of international norms on the use of chemical weapons. If the Government of Syria does not sign the Convention within 45 after the date of the enactment of this resolution, all elements of national power will be considered by the United States government.”

"Not later than 45 days after the date of the enactment of this resolution, the President shall submit to Congress a long term strategy for Syria, while concurrently using all appropriate diplomatic tools to develop and secure commitments from the international community with the shared strategic interest of preventing the proliferation and use of Syria’s chemical weapons."

“This is a draft proposal Senator Heitkamp is working on to approach the very complex situation in Syria. It is one idea that is still a work in progress," said her spokeswoman, Abigail McDonough.

The senator canceled a week's worth of public events in North Dakota to return to Washington to begin reviewing information on Syria. She and five other Democratic lawmakers attended a meeting in the White House Situation Room Thursday afternoon with Vice President Biden, who sought to persuade them to support military action. She has also met with outside experts at various D.C. think tanks, aides said. But Heitkamp remains undecided on how to vote on the resolution approved by the Senate Foreign Relations Committee authorizing a limited military strike on Syria in response to the use of chemical weapons.

Aides to Manchin declined to comment on the draft resolution Thursday night. Earlier in the day, he announced that he is opposed to the resolution. He canceled a week of public appearances in West Virginia to return to Washington to attend public and closed-door briefings on the situation. Before announcing his opposition Thursday, he told reporters that he had been speaking with current and former U.S. officials about Syria.

Always eager to seek bipartisan consensus among his colleagues, Manchin most recently brokered a bipartisan deal with Sen. Patrick Toomey (R-Pa.) on federal background checks for commercial firearm sales, but the agreement failed to help advance a far-reaching gun-control measure.

News of the Manchin-Heitkamp proposal was first reported by Politico.

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