A new constitution will not end all the violence in Iraq, Defense Secretary Donald H. Rumsfeld (search) said Tuesday, acknowledging that the continuing turbulence "has to be a be a heart-wrenching thing" for the families of U.S. forces still fighting insurgents there.

"The process has been delayed a bit, but democracy has never been described as speedy, efficient or perfect," Rumsfeld said during a Pentagon briefing. Earlier, Iraqi lawmakers delayed a vote on the draft constitution to give negotiators more time to persuade Sunni Arabs (search)to accept it.

The head of the committee drafting Iraq's constitution said an extra three days may be not enough to win over the Sunni Arabs and that the constitution may have to be approved by parliament as is and taken to the people in a referendum.

Rumsfeld dismissed the idea that objections from Sunnis could lead to civil war. President Bush, asked earlier about the possibility that a constitutional conflict could trigger a civil war, said: "The Sunnis have got to make a choice: Do they want to live in a society that's free?"

Rumsfeld said the Pentagon expected more insurgent attacks as the country finalized its constitution and attributed the high number of deaths in a fraction of them to insurgents "becoming more sophisticated" in developing deadly explosives.

He rejected the idea that the United States has gotten bogged down in Iraq like it did in Vietnam, saying polls show that anger toward the instability caused by insurgents is growing.

"Regrettably, completing the constitution is not likely to end all the violence in Iraq or solve all the country's problems," he said.

Rumsfeld said he would tell families of fallen soldiers like anti-war protester Cindy Sheehan that their sons and daughters have contributed to the liberation of millions of Iraqis, who no longer live under "mass murders and beheaders."

"It has to be a heart wrenching thing for each of the families involved," he said.

Sheehan has been maintaining a vigil outside Bush's ranch, a demonstration that has been joined by more and more other anti-war protesters.

Rumsfeld also rejected the idea that polls indicating growing dissatisfaction among American with the war might force the United States to give up the effort.

"That would be a return to darkness," he said.

Rumsfeld predicted that the base closing commission that will begin making its final decisions this week will "endorse the overwhelming majority" of the Pentagon's recommendations.