Following last week's warning of "credible intelligence" that al-Qa'eda is planning to disrupt the Nov 2 poll, counter-terrorism officials have admitted that they are looking into what legal steps would be necessary to delay the vote.
While the White House yesterday played down the chances of a delay, the news of the deliberations provoked a furious debate over the correct response to terrorism.
Democrats argued that planning for a possible postponement was over the top, citing the elections held on schedule in the Civil War and the Second World War.
They fear that public jitters over terrorism will boost President George W Bush's standing and, while anxious not to seem too relaxed, privately suggest that the warnings are based more on politics than real security concerns.
"I don't think there is an argument that can be made for the first time in our history to delay an election," said Senator Dianne Feinstein, a Democratic member of the Senate Intelligence Committee.
But Republicans suggested that the planning was a prudent response to allow for the "doomsday scenario" of another terrorist outrage.
"We don't have any intelligence to suggest that it is going to happen, but we're preparing for all of these contingencies now," Representative Christopher Cox, the Republican chairman of the House of Representatives Homeland Security Committee, told CNN.
He noted that New York election officials successfully postponed a primary election scheduled for September 11, 2001 after the hijackers flew two airliners into the World Trade Centre. "There isn't anybody that has that authority to do that for federal elections," he added.
According to Newsweek magazine, the deliberations began when a senior election official wrote to Tom Ridge, the Homeland Security Secretary, to point out that there was neither precedent nor planning for the postponement of a presidential vote.
DeForest Soaries, the chairman of the US Election Commission, which was set up after the disputed 2000 election to deal with logistical difficulties on polling day, said no federal agency had the authority to take the decision.
He suggested that Mr Ridge ask Congress to delegate the appropriate powers.
Mr Ridge gave warning last week that al-Qa'eda was plotting a "large-scale" attack to derail the election. But he conceded that there was no precise information about "time, place and method of attack".
With Mr Bush's re-election chances appearing at the moment to depend on public perceptions on the fight against terrorism and the war in Iraq, he launched a fresh defence of his record yesterday.
He travelled to Oak Ridge, Tennessee, to a plant storing parts of Libya's dismantled nuclear weapons programme. "Although we have not found stockpiles of weapons of mass destruction, we were right to go into Iraq," Mr Bush said.
The campaign of his rival, Senator John Kerry, has had a morale boost from his selection of Senator John Edwards as his running mate. But polls suggest an electoral boost of only a few percentage points.