President Barack Obama has called top congressional leaders to the White House, in a bid to stave off the rising threat of an historic US debt default.
Obama was expected on Monday afternoon (Tuesday morning AEDT) to meet top Republican and Democratic chieftains at the White House and demand Congress raise America's borrowing authority before a Thursday deadline.
The government itself meanwhile hit the two week mark of a partial shutdown which has damaged US prestige and will soon have an increasingly onerous impact on economic output.
Despite massive stakes for Washington and the world, there was still no clear path to resolving potentially the most serious impasse yet between Obama and Capitol Hill.
Initiatives in both the House of Representatives and the Senate stalled over the weekend, leaving the warring parties at odds with less than three days to run before the deadline.
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Obama will meet Republicans House Speaker John Boehner and Senate minority boss Mitch McConnell and Senate Democratic leader Harry Reid and the party's House minority leader Nancy Pelosi.
"The president will also reiterate our principles to the leaders: we will not pay a ransom for Congress reopening the government and raising the debt limit," the White House official said.
"The president continues to urge Congress to pass a bill that raises the debt ceiling and lends the certainty our businesses and the economy needs."
Only three days before the October 17 deadline to lift the debt ceiling, Washington appeared to be in strange and uncharted political waters.
"This environment is different than any that I have seen around an arrangement like this," Republican Senator Bob Corker told NBC's Today Show.
The uncertainty was mirrored on Wall Street, where increasing concern over the fiscal showdown pulled the Dow Jones Industrial Average down 57 points or 0.3 per cent in mid morning trade.
Yet there was little panic, but a sense that the wrangle over raising the debt ceiling would be eventually be solved at the eleventh hour - like many other recent political imbroglios.
Many eyes are now turning to veteran dealmakers Reid and McConnell as they seek to piece together a facesaving deal.
"I'm optimistic about the prospect for a positive conclusion," Reid said on Sunday.
The most likely scenario appears to be some kind of short-term deal to raise the debt ceiling for a number of weeks, and possibly to return thousands of federal furloughed workers to their jobs.
Republican Senator Roger Wicker told MSNBC he was hopeful of seeing "something meaningful by the end of the day".
"There are sweet spots that Republicans and Democrats agree on," he said.
Around the world, however, signs of alarm were mounting.
China and Japan - which between them hold more than $US2.4 trillion ($A2.55 trillion) of US debt - have urged Washington to get its house in order.
China's foreign ministry spokeswoman Hua Chunying took a chance in Beijing to wag its finger at Washington.
"The United States is the largest economy in the world and we hope that it can show its responsibility," Hua told reporters.
