BAGHDAD -- Nearly a year after pulling out of Iraq's "unity government," the country's main Sunni Arab political bloc returned to the Shiite Muslim-led Cabinet on Saturday, in a breakthrough for efforts to mend relations between the country's largest religious communities.

The decision represented a victory for Shiite Prime Minister Nouri al-Maliki, who earlier this year was facing calls for a vote of no confidence over his failure to build an effective governing coalition.

U.S. and Iraqi officials hope the Sunni bloc's return to the Cabinet will help consolidate recent security gains and give momentum to negotiations on an election law and other key power-sharing legislation. But it remains to be seen whether al-Maliki's selections will be considered representative of the disaffected Sunni minority, which until recently was the driving force in Iraq's deadly insurgency.

Analysts said al-Maliki's successes on the political and security front probably played a part in the decision by the Iraqi Accordance Front, known in Arabic as Tawafiq, to return to the Cabinet ahead of provincial elections promised for the fall.

It came the day after the White House said President Bush had agreed to set a "general time horizon" for withdrawals of U.S. combat troops from Iraq. Al-Maliki had been pressing U.S. officials for a timeline after facing a domestic backlash over negotiations for a deal governing U.S.-Iraq relations after the U.N. mandate for foreign troops in Iraq expires at the end of the year.

"With Maliki gaining in stature and now appearing to have reached an agreement with Washington regarding a timetable for troop withdrawals, Tawafiq risks being left behind if it does not come back in," said Vali Nasr, a professor of international politics at Tufts University.

Parliament on Saturday overwhelmingly approved the appointment of six members of the Accordance Front to ministerial positions, including a deputy prime minister's slot. Four independent Shiites also were approved to fill posts vacated by followers of populist Shiite cleric Muqtada al-Sadr.

Al-Maliki's Cabinet has been a unity government in name only since the front yanked its six representatives in August, accusing the dominant Shiite factions of refusing to share power.

At the time, members of al-Maliki's inner circle accused the bloc of harboring terrorists and said the prime minister's conversations with Sunni Vice President Tariq Hashimi frequently turned into shouting matches.

Hashimi remained in his position after the rest of the bloc pulled out of government and took a leading role in negotiations for its return. Al-Maliki now makes major decisions in consultation with the country's ethnic Kurdish president and two vice presidents, one of whom is Sunni and the other Shiite.

Another Sunni demand was met in February, when Parliament approved a conditional amnesty that cleared the way for thousands of detainees to be released from Iraqi jails. Most of those in detention are Sunnis, many of them captured in security sweeps at the height of the insurgency.

Sunni politicians also were reassured by a series of government crackdowns against Shiite militiamen, which began in March. Tawafiq had accused al-Maliki of failing to go after fellow Shiites as aggressively as he pursued Sunni insurgents.

The bloc's return to Cabinet was delayed by wrangling over who would occupy its seats, which include the ministers of culture, communications and higher education, and the ministers of state for foreign and women's affairs.

They will join two other Sunnis in the Cabinet: Defense Minister Abdul-Qader Obeidi, an independent, and Planning Minister Ali Baban, who was expelled from Tawafiq for refusing to quit his post.

Left out of the mix were members of the so-called Awakening movement made up of Sunni tribal leaders, whose rebellion against religious militants the U.S. military credits with helping bring down the level of violence nationwide. Awakening leaders have been pressing for a stake in power, and frustration is building at al-Maliki's failure to embrace the movement.

On the Shiite side, al-Sadr's representatives took issue Saturday with the candidates selected to replace them in the Cabinet, alleging that some had ties to al-Maliki's political alliance. Along with members of several smaller parties, al-Sadr's followers initially refused to take their seats for Saturday's vote. But when it became clear that there would be a quorum, many returned to the room.

Al-Sadr was one of al-Maliki's main backers when he was named prime minister. But the cleric pulled his representatives out of Cabinet in April 2007 when al-Maliki resisted his demands for a timetable for the withdrawal of U.S.-led forces from Iraq. Al-Maliki later reversed course and began pushing for the timeline.

On a visit Saturday to Baghdad, British Prime Minister Gordon Brown said plans are also being made to scale back Britain's troops in Iraq. But he refused to consider an "artificial timetable" for withdrawing the 4,000 remaining British troops.