With some Sunni leaders calling for an election boycott, their lack of representation in any new legislature could further accentuate their minority status, not least because Shia clerics have been calling for a mass turnout. With most violence focused in Sunni areas, security fears will also minimise turnout among Sunnis and discourage some candidates from standing.
"There's some flexibility in approaching this problem," a White House official told the New York Times. "There's a willingness to play with the end result - not changing the numbers, but maybe guaranteeing that a certain number of seats go to Sunni areas even if their candidates did not receive a certain percentage of the vote."
Some are deeply critical, claiming the move illustrates the problems Washington is having in persuading Iraqis about the legitimacy of the January 30 poll.
"This idea is a non-starter," said Feisal al-Istrabadi, Iraq's deputy permanent representative at the UN.
"But what it tells you is that inherently people are concerned about the problems with respect to legitimacy of the elections, not because people are going to boycott, but because people are going to be afraid to vote."
Although Sunni Muslims comprise just 20% of the population they dominated Iraqi politics under Saddam Hussein, whereas the majority Shia were routinely discriminated against.
The US now fears a low Sunni turnout.
"We are doing everything we can ... to encourage maximum Sunni participation in the election," the secretary of state, Colin Powell, said last week.
"If we get a fairly decent Sunni turnout ... that would be good for the country and good for the process. If it was nobody at all, I think that would be problematic. But I don't expect it to be nobody at all."
Talk of guaranteeing Sunni representation has not been raised officially but, according to several sources within the state department, it is being seriously discussed both in the US and in Iraq.
Some American diplomats believe it is in their long-term interest to guarantee a minimum level of Sunni representation.
"You do the math," said Larry Diamond, a senior fel low at the Hoover Institution at Stanford University and a former adviser to the US-led occupation in Baghdad.
"Iraq's population is about 60% [Shia], 20% Sunni and 20% Kurd. But if Sunnis don't vote, they could become only 5% of the electorate."
Iraqis must choose from 107 groupings and parties, and some 7,000 candidates.
If Sunnis were marginalised in that fashion, Mr Diamond said, it could lead to further alienation and an increased insurgency, and possibly prompt a civil war, especially if the Kurdish and Shia victors tried to write a constitution that favoured their interests.
"Suppose that the violence is so bad that even if candidates are brave enough to stay in the race, but voters don't turn out, Sunni candidates in the end win very few seats," Mr Diamond told the New York Times. "One thing you could see happen, I think, is some of these Sunni candidates withdrawing because their base isn't going to turn out."
Some Sunnis have called on the US and the Iraqi interim government to postpone the election while security improves - a request that has repeatedly been rejected by the Bush administration.
Instead, US officials have been mixing threats and promises to force the Sunnis to the polling station and on to the ballot papers.
"The Sunnis would have to live with their own decisions if they boycott," one official told the Los Angeles Times. "Do they really want ... a civil war against a Shia population that outnumbers them three to one?"