Iraq's Sunni Arab minority faces a choice between peace and violence, US President George W Bush has warned.
Mr Bush has repeated his core messages on Iraq
Mr Bush urged Sunnis to accept a deal that secured peace, with agreement on a new constitution apparently no closer as Thursday's deadline nears.
Iraq's transition from dictatorship to democracy was happening at a rapid pace, Mr Bush said, and could herald wider change in the Middle East.
Sunnis say that the draft constitution does not represent all their interests.
Mr Bush has been facing domestic pressure to demonstrate a political or military success in Iraq, with opposition to the continuing conflict growing at home.
He said it was no surprise that Iraqi leaders were having difficulty agreeing a compromise position.
"We're watching an amazing event unfold, and that is the writing of a constitution which guarantees minority rights, women's rights, freedom to worship in a country that only knew dictatorship."
He said Sunnis should turn away from suggestions of rejecting the constitution, which has been hamstrung by disagreements over federalism for Iraq's Shias, as well as the structure of a future executive government.
"You talk about the Sunni rising up, the Sunnis have got to make a choice - do they want to live in a society that's free, or do they want to live in violence?"
Sunni leaders, many of whom held key positions under Saddam Hussein, are seen as influential in ending the insurgency still raging across Iraq.
Their acceptance of the constitution is seen as vital in avoiding possible sectarian conflict in Iraq.
He rejected calls by anti-war campaigners such as Cindy Sheehan, who has set up camp outside Mr Bush's Texas ranch, for the US to bring home troops.
"I appreciate her right to protest. I understand her anguish," he said of Mrs Sheehan.
"I think immediate withdrawal from Iraq would be a mistake. I think those who advocate immediate withdrawal from not only Iraq, but the Middle East, are advocating a policy that would weaken the United States."