Iraq's president has insisted elections should go ahead next month as planned and the United States said it would send thousands more soldiers to provide extra security for the ballot.
The US military will temporarily boost its troop strength in Iraq to about 150,000 from 138,000 for the election set for January 30, US defence officials said.
"There will be some short-term deployments of additional troops to help with security," an official said in Washington.
"This will all boost our military presence to about 150,000 over the short term."
Iraq's president, Mr Ghazi al-Yawar, said the election should go ahead on time, distancing himself from other leading Sunni Arab politicians who are demanding the polls be put off to a later date because of widespread unrest.
Mr Yawar, a Sunni businessman and tribal elder appointed to the largely symbolic post of president in June, is the first prominent Sunni to reject calls for a postponement.
"We must go ahead with elections, from a legal and a moral point of view... it's my personal view they should go ahead on time," Mr Yawar told a news conference in Baghdad.
Iraq's interim constitution, endorsed by the United Nations, says elections must be held by the end of January to select a transitional assembly which will pick a new cabinet and oversee the drafting of a permanent constitution.
The US military says it will crack down on insurgents in rebel strongholds by the end of the year to improve security in time for the elections.
Today, US Marines fought off Iraqi insurgents who attacked them with mortars during a series of raids to hunt down arms and guerrilla suspects south of Baghdad.
Hundreds of US and British troops raided farms and homes in a fertile stretch of the Euphrates Valley where support for Saddam Hussein used to be strong, and detained 15 people.