Iraqi Shia Muslim leaders have warned against revenge attacks following two bombings in the cities of Najaf and Karbala that killed at least 60 people.
The Karbala blast took place in a crowded bus station
The two powerful car bomb blasts are believed to have been carried out by Sunni Muslim insurgents.
Respected Shia cleric Mohammed Bahr al-Uloum said Shias - the majority in Iraq - were committed to peaceful participation in next month's election.
Officials have warned of an increase in violence ahead of the 30 January poll.
Sunday also saw three Iraqi election workers dragged from their car and shot dead in Baghdad.
Scenes of horror
The bomb attacks in two of Shia Islam's holiest cities claimed the highest number of civilian deaths in a single day since July.
At least 48 people died and 90 were injured in Najaf when a car bomb tore through a square near the Imam Ali shrine compound, one of Shia Islam's most revered sites.
Crowds had gathered in a main square for the funeral procession of a tribal sheikh.
A similar explosion at a crowded bus station in Karbala left 13 dead and 30 wounded.
One of Najaf's leading Shia clerics, Grand Ayatollah Mohammed Said al-Hakim, denounced the bombings.
He said they aimed to "incite sectarian sedition" and that God would "avenge and compensate" the victims.
Mr Bahr al-Uloum urged Shias not to avenge the killings, and stay focused on the elections.
"The Shias are committed not to respond with violence, which will only lead to violence. We are determined on elections," he said.
And a spokesman for the movement led by the militant Shia cleric Moqtada Sadr said civil war would be "hell".
Shias make up about 60% of Iraq's population and hope the elections will reverse the long-time dominance of the Sunni minority.
Sunni insurgents are believed to be behind much of the violence, in an attempt to derail the US-backed elections.
Saddam urges boycott
Some Sunni leaders have threatened to boycott the elections as a protest against the US-led offensive in the predominantly Sunni city of Falluja, an insurgent stronghold until the assault.
They also fear continued clashes between US troops and insurgents in Sunni areas could prevent many people from voting.
The poll is set for 30 January
Respected Sunni politician Adnan Pachachi, who is standing in the election, repeated his call for a "short postponement" of the poll to address their concerns.
"I think this would help to ameliorate the whole security
situation," he said.
Electoral commission spokesman Farid Ayar said the violence and Sunday's attack on poll workers would not stop the election going ahead as planned.
But he did say security measures would be improved to give greater protection to election workers.
"I think most Iraqis... want to go to the election centres and give their vote to the candidate they like. This encourages us to go on with the process to the end," he said.
From his prison cell, former Iraqi President Saddam Hussein has urged Iraqis to boycott the elections and "confront US plans to divide their country on sectarian grounds".