Parliament in Baghdad has delayed voting on a request to grant the prime minister emergency powers as the north slips out of government control.
Just 128 out of the 325 MPs turned up for the vote on Nouri Maliki's request.
In the north, Kurdish forces claimed control of the oil city of Kirkuk, saying government forces had fled.
The Kurds secured the area after the cities of Mosul and Tikrit fell to Sunni Islamist insurgents during a lightning advance.
Kurdish fighters are seen as a bulwark against the Sunni Muslim insurgents but they have also been locked for years in a dispute with Baghdad over Kirkuk, seeking to incorporate it into their own autonomous area.
Led by the Islamic State in Iraq and the Levant (ISIS), the insurgents are believed to be planning to push further south to the capital, Baghdad, and regions dominated by Iraq's Shia Muslim majority, whom they regard as "infidels".
The Iraqi prime minister is believed to be asking for powers to impose curfews, restrict public movements and censor the media.
The failure of the parliament to achieve a quorum says much about the fragmented state of Iraqi politics, the BBC's Jim Muir reports from Kurdish-run Irbil.
The onslaught by Sunni militants has produced many calls for national unity but little sign of anything practical to turn the tide, our correspondent says.
Meanwhile, he adds, the Kurds are clearly happy to fill the vacuum in Kirkuk - an area they historically claim as theirs.
The Kurdish minister in charge of security forces in Kirkuk survived a roadside bomb blast on Thursday after visiting the city and surrounding areas, according to Kurdish officials.
However, it appears the insurgents want to avoid tangling with Iraqi Kurds - a more cohesive fighting force - in provinces bordering Nineveh province where Mosul is located.
A new insurgent offensive could come from the west, where they control the city of Falluja, 69km (43 miles) from Baghdad, our correspondent says.
ISIS in Iraq
- The Islamic State in Iraq and the Levant (ISIS) has 3,000 to 5,000 fighters, and grew out of an al-Qaeda-linked organisation in Iraq
- ISIS has exploited the standoff between the Iraqi government and the minority Sunni Arab community, which complains that Shia Prime Minister Nouri Maliki is monopolising power
- It has already taken over Ramadi and Falluja, but taking over Mosul is a far greater feat than anything the movement has achieved so far
- The organisation is led by Abu Bakr al-Baghdadi - an obscure figure regarded as a battlefield commander and tactician. He was once the leader of al-Qaeda in Iraq, one of the groups that later became ISIS.
Security in Baghdad has been stepped up after a video emerged of the militants threatening to march on the capital.
Parts of Kirkuk province were overrun by the Sunni Islamists this week.
Government forces slowed the insurgents' advance on Wednesday outside Samarra, a city just 110km north of Baghdad.
However, according to AFP news agency's sources, the militants have since pushed even further south, bypassing Samarra and seizing the town of Dhuluiya, 90km north-west of Baghdad.
There are also reports of hundreds of police officers being arrested by the militants in Tikrit, located 140km from the capital.
In Mosul, the Islamist rebels have decreed new rules of conduct ordering all Muslim residents to attend the mosque for the five daily prayers, and banning alcohol and smoking. Police and soldiers have been told to repent or be killed.
Analysis: Dina Demrdash, BBC Arabic
Poor attendance in today's session is revealing how dysfunctional the parliament has become. Over the past few years, the legislative body has passed only few legislations, and they were of little significance.
The no-show in Iraq's fragmented parliament is adding to the woes of Prime Minister Nouri Maliki, who is being accused by political opponents of seeking too many powers.
But with a demoralised army as well as political foes regrouping, the parliament - where Mr Maliki's coalition holds at least 92 seats - should have been the least of his troubles.
The insurgents also control a large swathe of territory in eastern Syria, amid a campaign to set up a Sunni militant enclave straddling the border.
Washington says it is considering further assistance to Iraq in fighting the militants, without giving details.
Some US commentators have argued that Iraq is on the verge of disintegrating.
But Iraq's former Prime Minister, Ayad Allawi, warned against launching another foreign military intervention, saying air strikes could "add fuel to the fire".
"The international community should seek another alternative to get out of this mess," he told the BBC. "It is not a matter of creating yet again a big war in and around Iraq."
Meanwhile, Iran - which is predominantly Shia Muslim - warned it would "combat" the extremists in Iraq.
President Hassan Rouhani said he would not "tolerate" the rebels who were "acting savagely", ahead of a meeting with Supreme National Security Council.
The UN Security Council has condemned the attacks on Mosul and Tikrit. The humanitarian situation around Mosul, where up to 500,000 people have fled, was "dire and... worsening by the moment", it said.
Some of the civilians have sought refuge in the Kurdish provinces, while others streamed south along with retreating security forces to Baghdad.
In another development, funerals were being held on Thursday for victims of a suicide bomber who killed at least 15 people and injured 34 when he blew himself up at a funeral in Baghdad on Wednesday.
•Under Saddam Hussein's programme of "Arabisation", Kurds were driven from Kirkuk and replaced with settlers from the south, and the Iraqi government continues to assert control over nearby oilfields, with the backing from the local Turkmen community
•The Kurdistan Regional Government, which administers three provinces to the north-east, is pushing for Arabisation to be reversed
•In May 2013, Kurdish fighters took up positions on the outskirts of Kirkuk after Iraqi security forces were redeployed to deal with Sunni militants elsewhere
•A census and referendum on the affiliation of the province has been repeatedly delayed by the broader political crisis in Iraq.
Are you in the area? Are you from Kirkuk or Mosul? Have you been affected by the situation? You can email firstname.lastname@example.org using 'Mosul' in the subject.