The White House has expressed confidence Congress would back President Barack Obama's decision to carry out a military strike on Syria.
The Obama administration has evidence the Syrian government used lethal sarin gas on its own people, which killed thousands of people, including hundreds of children.
However, Obama and his inner circle worked furiously over the weekend to win congressional support, holding classified briefings and making calls to Capitol Hill leaders, Fox News reports.
A senior administration official said that Obama, Vice President Joe Biden and Chief of Staff Denis McDonough made phone calls to senators and House members urging them to vote in favor of the authorization of military strike in Syria.
The official called the lobbying effort a 'flood the zone' strategy, in an apparent acknowledgement of just how hard it will be to win Capitol Hill approval.
The effort was preceded by Secretary of State John Kerry, as Capitol Hill lawmakers said Obama may not have the votes right now.