Joe Biden, the US vice-president, has begun talks with Iraqi leaders amid tensions over a decision to bar candidates from upcoming elections over their suspected links to the outlawed Baath party.
Biden was due to meet Nouri al-Maliki, Iraq's prime minister, and Jalal Talabani, the country's president, on Saturday, to discuss the Iraqi move to exclude more than 500 politicians from the March vote.
A US official travelling with Biden said he was confident the furore would be resolved by the Iraqis themselves.
"I would say based on the recent months especially, that what we've seen is a growing and significant ability of Iraqis to resolve their differences and disputes through the political process," Antony Blinken, Biden's national security adviser, said.
"And so I don't think it's the place of the United States or any other outside country to resolve these kinds of problems for Iraqis because they are demonstrating they are more than capable of resolving it for themselves."
Biden's visit underscores Washington's concern that the growing sectarian tensions could seriously mar the election, which has been seen as an important step in healing Iraq's wartime divides and allowing the US to accelerate troop withdrawals.
Nasser al-Ani, Iraq's presidential spokesman, said Iraq was willing to listen to suggestions on easing the political standoff caused by the blacklist, but "nobody can interfere in Iraqi affairs ... Biden or others".
Ali al-Dabbagh, a spokesman for the Shia-led government, also drew a clear line on outside views over Iraq's efforts to identify and weed out suspected supporters of the outlawed Baath party, headed by Saddam Hussein, the former Iraqi president.
"It is an internal affair that should be discussed by Iraqi political entities,'' he said.
The list of banned candidates was drawn up by a panel charged with preventing high-ranking Baathists from returning to public life.
The names included Saleh al-Mutlaq, a popular Sunni politician, which triggered protests from minority Sunnis who complained that majority Shias were trying to marginalise them.
The panel's ruling, which was upheld by Iraq's independent electoral commission, still faces a court challenge.
Talabani said there would be a meeting in the coming days between the presidency, leaders of parliament, heads of the judiciary and al-Maliki to "find a legal and constitutional solution" to the row over the banned candidates.
The incident raised concerns about Iraq's fragile security with the parliamentary election less than seven weeks away.