A delegation from Iraq's national conference has gone to the holy city of Najaf to try to end a bloody Shia uprising. Security concerns delayed the group's departure and reduced the number of representatives who went.

Conference participants and organizers say security concerns kept the delegation in Baghdad, despite a message from radical Shia cleric Moqtada al-Sadr that he would be willing to receive them. It was late afternoon when the man leading the delegation, the cleric's more moderate kinsman Hussein al-Sadr, told reporters in the packed convention center that the group was about to leave.

Mr. al-Sadr said, "Yes, yes, we are leaving soon." He then said he had no time to answer any more questions and abruptly left the room.

Shortly afterward, an eight-member group flew by helicopter to Najaf bearing a message from the conference delegates. They want Moqtada al-Sadr's militia to disarm and leave the Shrine of Imam Ali, one of the holiest sites in Shia Islam, in exchange for amnesty. They are urging the radical cleric to turn his militia, the Mahdi Army, into a political party.

United Nations adviser Ibrahim Nawar, who helped organize the conference, says it is important that the mediation effort succeed.

"You cannot ignore it. If you have a situation like that in one part of the country, and this is the national conference. It has a responsibility," said Mr. Nawar. "So it has to move and do something. And it is down to these people, the delegates, not to achieve victory for themselves, but to try to prove that this body is credible, and can achieve something, and can be trusted [by] the Iraqis."

The conference has been a chaotic experiment in democracy, and many participants have struggled to figure out how exactly they were to carry out their main task, choosing 81 members of the interim National Council, which is to oversee the workings of the interim government.

The procedure laid out by conference organizers required delegates to submit lists of 81 people representing of all parts of Iraqi society. They would then vote on the lists. But since many of the delegates come from smaller parties, civic groups, and far-flung provinces, they have not all had time to get to know each other, which has made it harder for them to decide who to put on their lists.

Samir Shakar Sumaiday heads a political party known as the Patriotic Democratic Alliance. He says it has been a challenge just compiling the lists, and many of the smaller parties feel sidelined by the bigger groups.

"This is the subject of deals and backroom discussions, and this is making people who are not part of this process unhappy because they are finding themselves being left out. Of course, in theory, every member of this conference is free to form his own list," he said. "But people have no time to do that."

And so toward the end of the day, it was still not clear whether the conference would continue on into the night, be extended for another day, or just go ahead with the vote in an effort to bring the process to an end on time.

Earlier in the day, several mortar shells landed near the conference center. One of Moqtada al-Sadr's aides, who was on his way to the conference to discuss the situation in Najaf when the shell hit, said he was slightly wounded by flying shrapnel, as were two other people.

A mortar attack in another part of the city killed at least seven people and wounded scores more when the round landed in a busy commercial district.