President Bush spoke to seven Iraqi political leaders on Saturday in an effort to defuse the sectarian violence that threatens the goal of a self-sufficient Iraq free of U.S. military involvement.

Bush's extraordinary round of early morning telephone diplomacy involved his first conversations with Iraqi leaders since the bombing of a revered Shiite shrine that prompted days of reprisal attacks.

There are fears in Baghdad and Washington alike that Iraq could be on the brink of civil war nearly three years after the U.S. invasion ousted Saddam Hussein's regime. The violence put a halt to talks on the formation of a unity government, a step regarded as key to demoralizing the Sunni-dominated insurgency and setting the stage for the end of the U.S. military presence there.

"The president congratulated Iraq's leaders for their strong leadership and their efforts to calm the situation and for their statements against violence and for restraint," said Frederick Jones, a spokesman for the White House's National Security Council.

Bush "encouraged them to continue to work together to thwart the efforts of the perpetrators of the violence to sow discord among Iraq's communities," Jones said.

In calls that took place over about an hour, Bush did not speak with any of Iraq's influential religious leaders. Instead, he chose the most powerful representatives of each of Iraq's main political groups: Iraqi Prime Minister Ibrahim al-Jaafari, a Shiite; the head of Iraq's largest Shiite political party and the country's most powerful Shiite politician, Abdul-Aziz al-Hakim; Iraqi National Assembly president Hajim al-Hassani, a Sunni; Tariq al-Hashemi, a leader of the main Sunni coalition; Ayad Allawi, a former Iraqi premier who's a secular Shiite with Sunni allies; Iraqi President Jalal Talabani, a Kurd; and Kurdish leader Massoud Barzani.

Bush pressed each of the leaders to find a way to restart U.S.-backed negotiations among Shia, Sunni and Kurdish leaders to fashion a permanent government. The largest Sunni Arab bloc in parliament said Saturday it will reconsider its decision to pull out of the talks if al-Jaafari follows through on promises that the government will act to ease the crisis.

"The president underscored his support for Iraq's efforts to build a government of national unity," Jones said.

Bush expressed his condolences for Wednesday's bombing of the golden-domed Askariya Shrine in Samarra and the cycle of retaliatory attacks that followed, Jones said. Nearly 200 have died, and scores of Sunni and Shiite mosques have been damaged.

Extraordinary security measures have been in place, including a daytime curfew and bans on some travel. Shiite and Sunni leaders have called for unity between the sects. Still, there was a surge of new attacks on Saturday.

The White House chose to focus on the positive and disputed that there had been a resumption in violence.

"The president has been pleased with the restraint shown," Jones said.

He would not comment on why the president felt compelled to make the calls, or provide any detail on what any of the leaders told Bush about what could be done.