The two US presidential candidates have urged changes to a $700bn (£382bn) bail-out of the US banking system but stopped short of rejecting it outright.
Republican John McCain and Democrat Barack Obama both called for greater oversight and voiced concern that ordinary taxpayers should not lose out.
Their comments came as the bail-out plan met scepticism from both parties at a Senate banking committee hearing.
Meanwhile, a new poll suggests Mr Obama may be opening a lead over his rival.
Analysts say the Illinois senator is benefiting from the turmoil in the US economy, with voters saying they trust him more than Mr McCain to handle the crisis.
The two candidates will meet face-to-face in the first of three presidential debates on Friday, due to focus on foreign policy.
'Country first'
On Tuesday, Mr Obama and Mr McCain each demanded guarantees of greater oversight of the plan, under which a federal fund could buy bad debt from financial institutions.
At the same time, Mr McCain warned that time was running short for Congress to take action to avert further economic pain.
"The power to spend $700bn of taxpayer money cannot be left to the discretion of one man" Barack Obama"Inaction is not an option. The American people are watching, history will be our judge and it will judge us harshly if we do not put our country first," he told a news conference in Michigan as he suggested his changes to the plan.
He said Congress must be sure that the bail-out, presented to the senate banking panel by Treasury Secretary Henry Paulson, would not reward Wall Street executives at the expense of US home-owners.
Mr Obama, speaking in Florida, echoed that message as he set out his proposed amendments to the plan, including the demand that a board be set up to oversee its administration.
He said: "The power to spend $700bn of taxpayer money cannot be left to the discretion of one man, no matter who he is or which party he is from.
"I have great respect for Secretary Paulson but he cannot act alone."
Mr Paulson and Federal Reserve Chairman Ben Bernanke are due to testify to a House of Representatives committee on Wednesday.
Economic edge
Meanwhile, a Washington Post-ABC News national opinion poll released on Wednesday put Mr Obama nine points clear of Mr McCain, with 52% support to his 43% among likely voters.
Two weeks ago, polls suggested the two candidates were neck-and-neck.
According to the Washington Post newspaper, half of those surveyed said the economy and jobs were the most important issues in deciding their vote, up from 37% a fortnight ago.
The poll suggested Mr Obama had a big edge - 14 points over Mr McCain overall and 21 points among independent voters - as the candidate more in tune with the economic problems voters faced.
Mr McCain and his running mate, Alaska Governor Sarah Palin, are jointly to meet the presidents of Georgia and Ukraine on Wednesday at the United Nations General Assembly in New York.
Mrs Palin, who is widely seen as seeking to bolster her foreign policy credentials, met Afghan President Hamid Karzai, former Secretary of State Henry Kissinger and Colombian leader Alvaro Uribe on Tuesday.
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