US politicians have spent the day scrambling to secure support for the proposed 11th-hour deal to raise the country's national borrowing limit, while some remained opposed to the deal.
The $2.1 trillion (£1.28 trillion) deficit-cutting plan, brokered by vice president Joe Biden and Republican and Democratic congressional leaders, is headed for a close vote in the House of Representatives.
Ahead of the vote, scheduled for this evening, the House has enough Yes votes to approve the rule for debating the landmark legislation. The rule allows for one hour of general debate before a vote on the actual bill.
Biden said earlier he was "confident" of passing the bill needed to raise the country's national debt ceiling tonight, following a two and a half-hour crunch meeting with Democrats in the House of Representatives.
Biden told reporters he went to Capitol Hill to explain the deficit reduction and debt limit increase legislation he helped to broker.
"I am confident that this will pass," he said, but added that under different circumstances "we would be talking about job creation, infrastructure (investment)."
Leaders of both parties have worked furiously to sell their rank-and-file on a deal reached with president Barack Obama in a bid to end an acrimonious impasse.
Just one day before the deadline to lift the debt ceiling, the Democrat-led Senate appears on track to pass the deficit-cutting plan.
But uncertainty over its fate in the Republican-controlled House of Representatives has rattled financial markets worldwide and left the US facing a credit rating downgrade regardless of the vote outcome.
"The deal does not put the US fiscal position on a sustainable path and will not prevent the US from losing its AAA credit rating," said Capital Economics economist Paul Dales.
"The combination of less than $1 trillion in deficit reduction being “in the bag” and the other $1.5 trillion not yet guaranteed falls short of the “credible solution” involving “a medium-term fiscal consolidation plan of $4 trillion” that S&P has implied would be necessary to prevent a rating downgrade."