The Democratic and Republican US presidential candidates have urged congress to agree on a deal to bail out US financial firms after the House of Representatives rejected such a bill.
Barack Obama, the Democratic candidate speaking at a rally in Colorado, urged politicians to "get this done", while John McCain, his Republican rival, said in a campaign speech in Iowa that congress needed to "go back to the drawing board" to solve the problem.
Obama said he was confident that a bail-out deal would be struck but that "it's going to be a little rocky".
"It's important for the markets to stay calm because things are never smooth in congress and to understand that it will get done," the Illinois senator said on Monday after the house rejected the bill.
Shares on Wall Street plummeted, with the Dow registering its steepest points fall - 777.68 - in history and the S&P 500 having its worst day in 21 years.
'Partisan' politics
Republican and Democratic opponents of the government's proposition to offer struggling US financial firms a $700bn bail-out combined to doom the bill by 228 votes to 205, despite George Bush, the US president, pressing for its passage.
McCain took aim at Obama, who he accused of sabotaging the bill by introducing partisan politics into the discussions.
"Senator Obama and his allies in congress infused unnecessary partisanship into the process," he said after the House of Representatives rejected the bill.
"Our leaders are expected to leave partisanship at the door and come to the table to solve our problems.
"Now is not the time to fix the blame, it's time to fix the problem."
A number of US financial firms have faced collapse after receiving losses stemming from the sub-prime mortgage crisis, when people took out high-interest loans they were unable to repay.
The losses have spread to international financial firms, causing chaos in global markets.