A session of Iraq's parliament planned for Monday has been postponed amid continuing deadlock over the PM.
Dozens of people were killed and injured across Iraq on Sunday
MPs were to meet for only the second time since December's election but the acting speaker said leaders needed more time to resolve their differences.
Kurdish and Sunni parties are refusing to back the Shia nominee for premier, the incumbent Ibrahim Jaafari.
Meanwhile violence shows no sign of abating, with at least 34 people killed across Iraq on Sunday.
Sunni Arab and Kurdish groups have demanded that the main Shia alliance must replace Mr Jaafari as its candidate, arguing that he is a divisive figure who has failed to end the unrest.
Shia parties have also come under growing pressure from the United States to drop their support for Mr Jaafari.
But Mr Jaafari has repeatedly refused to stand aside and the Shia alliance is yet to agree another candidate.
Iraq's ambassador to Washington, Samir Sumaidaie, said a solution to the deadlock could be found in the next few days.
He said the leading contender for this was a legislator from Mr Jaafari's own party, Ali al-Adib.
Iraq's parliament was elected on 15 December but had only one brief session last month.
The Shia alliance emerged as Iraq's largest political group, with 128 out of 275 seats.
Violence continued across Iraq on Sunday.
At least 10 people were killed and 20 injured when a car bomb exploded in Mahmudiya, about 30km (20 miles) south of the capital, which has a mixed population of Sunni and Shia Muslims.
Further north, in Mosul, gunmen killed seven construction workers and wounded three others, police said.
At least four people were killed by gunmen near Baquba, north of Baghdad, and three died when a minibus was bombed in the capital itself.
Iraqi politicians, the US administration and political observers have said the establishment of an Iraqi government is essential if Iraq is to become less dangerous.
The BBC's James Reynolds in Baghdad says many Iraqis are questioning whether releasing a list of people for cabinet roles will really derail the insurgency.
But the hope, he says, is that once Iraqis realise they are being represented, the country will stabilise from the top down - though it may take many months.