Iraq's outgoing interior minister predicted Monday that his country's emerging police and army may be capable of securing the nation in 18 months, saying his officers are beginning to take over from coalition forces.

Insurgents, meanwhile, targeted Shiite pilgrims, setting off two blasts that killed at least three people.

Interim Interior Minister Falah al-Naqib's (search) comments came as security was heightened in the already heavily fortified Green Zone, where the National Assembly will hold its long-awaited second session Tuesday to choose a parliament speaker and two deputies.

Negotiators haggled over who would get the parliament speaker job, considering interim President Ghazi al-Yawer (search). They hope the inclusion of Sunni Arabs like him in the new government will help quell the Sunni-led insurgency.

But al-Yawer turned down the post and instead asked the Shiite-led United Iraqi Alliance (search) for the vice president's post, said Ali Faisal, political coordinator for the Shiite Political Council, which is part of the alliance.

Alliance members agreed to nominate former nuclear scientist Hussain al-Shahristani as one of two deputy parliament speakers and interim Finance Minister Adel Abdul-Mahdi as one of two vice presidents.

Alliance negotiator Jawad al-Maliki said the Sunni Arabs were expected to name a candidate for the parliament's speaker position Tuesday.

Al-Naqib predicted that militants will target Tuesday's National Assembly meeting — only the second since the parliament was elected nearly two months ago in the nation's first free election in 50 years. The lawmakers met March 16 but repeatedly have postponed a second meeting because of negotiations over Cabinet positions.

Roads were blocked off Monday, and security was tightened around the area, already surrounded by concrete blast walls and barbed wire. Several mortar rounds slammed into the banks of the Tigris River, just short of the Green Zone (search).

Underscoring tensions with the country's majority Shiites — who make up 60 percent of Iraq's estimated 26 million people — insurgents set off two explosions targeting Shiite pilgrims heading to Karbala for a major religious ceremony.

In Musayyib, 40 miles south of Baghdad, a suicide bomber on a bicycle blew himself up near a police patrol protecting the pilgrims, Capt. Muthana al-Furati of the Hillah police force said. Two policemen were killed. The attack wounded two other officers and three civilians.

The other bombing took place at the Imam al-Khedher shrine compound in Khalis, 50 miles north of Baghdad. The attack killed one pilgrim and wounded two others resting at the compound, Col. Abdullah Hessoni Abdullah said.

Pilgrims travel to Karbala to mark al-Arbaeen, the end of a 40-day mourning period after the anniversary of the 7th-century martyrdom of Imam Hussein, one of the Shiite religion's top saints.

In a news conference, al-Naqib outlined progress by the country's fledgling security forces, predicting that U.S. troops would be able to begin slowly pulling out of parts of the country, and that "hopefully, within 18 months at the most we will be capable of securing Iraq."

"We hope that next summer, there will be a huge reduction in the numbers of multinational patrols," he said. "In some cities, there will be no foreign troops at all."

He said Iraqi police had better intelligence on local insurgents and criminal gangs that have flourished since the March 2003 U.S.-led invasion, helping reduce the number of casualties caused by car bombs and other attacks.

"I think it will collapse very soon," he said of the country's insurgency.

The interior minister added that Iraq's most-wanted terrorist, Abu Musab al-Zarqawi, "has been surrounded in more than one area, and we hope for the best."

Al-Zarqawi's organization has claimed responsibility for kidnappings and killings across Iraq. On Sunday, militants posted a video on the Internet showing the purported execution of a man identifying himself as Interior Ministry official Col. Ryadh Gatie Olyway. The authenticity of the tape could not be verified.

Al-Naqib gave no timeline for a complete U.S. withdrawal, something U.S. officials have repeatedly said hinges on the security situation in Iraq and the wishes of the Iraqi government.

In an interview Sunday with CNN's "Late Edition," Army Gen. John Abizaid, the commander of U.S. Central Command, said Iraqi forces had made progress although challenges remained.

"By the end of 2005, provided the political process continues to be successful, you will see the Iraqis more and more in charge, and in some areas completely in charge," Abizaid said.

He also expressed concern about the delay in forming a new government, saying: "The more uncertainty, the greater chance for escalated violence."

Residents were already expressing frustration with the gap in governance, as some lame-duck ministries struggled to provide services. Tensions rose Sunday when bodyguards outside the Science and Technology Ministry shot at several dozen protesting employees demanding to be paid in full. One person was killed.

Some employees said they had only received partial paychecks.

Al-Naqib defended the actions, saying the demonstrators were trying to enter the ministry's offices and bodyguards simply were doing their jobs. Haithem Jassim, one of three people injured in the melee, said the demonstrators did not have any weapons.

Al-Naqib warned citizens not to protest, saying the gatherings were an invitation for a large-scale terrorist attack.

"Iraq has witnessed more bloodshed than it should," he said. "We are witnessing a situation in which Iraqi blood is becoming very cheap."