The White House withheld judgment on Friday on the latest proposal to break an impasse on an Iraq constitution (search) despite an attempt by President Bush to move the process forward with a phone call to a top Iraqi Shiite leader.

Bush called Abdul-Aiz al-Hakim (search) on Wednesday — Thursday in Iraq — to "discuss current developments," said White House spokesman Trent Duffy.

"It reflects ... that this is an Iraqi process and that the United States is here to help them," Duffy said.

Prodded by that call, Shiite negotiators Friday offered what they called their final compromise proposal to Sunnis Arabs (search) to try to break the impasse. In his call to al-Hakim, Bush urged consensus over a draft that has thus far been opposed by minority Sunnis, a Shiite official, Abbas al-Bayati, told The Associated Press in Baghdad.

Al-Bayati said the new offer included concessions on the pivotal issues of federalism and efforts to remove former members of Saddam Hussein's Sunni-dominated Baath Party (search) from public life. The Shiites (search) were awaiting a response from the Sunnis, al-Bayati said.

Duffy would not elaborate on what the two leaders discussed, or whether Bush planned more such personal diplomacy as negotiations continue. The president made the call on Wednesday in Idaho, where he had given a speech to military families, before he returned to his Texas ranch, Duffy said.

Asked about the proposed compromise by Shiite negotiatators, Duffy declined to comment.

"We're not going to be commenting on every wrinkle and bob and weave that goes on," Duffy said. "We support the process."

Amid declining poll standings and questions about how long U.S. troops will be kept in the wartorn country, Bush made two speeches this week. In addition to the appearance in Idaho, the president also gave a talk to the Veterans of Foreign Wars in Utah.

The president has repeatedly said that the United States cannot withdraw precipitately from Iraq, and that to do so would dishonor the sacrifice of the fighting men and women who have perished there.