The spokesman for Pakistan's election commission has said that holding parliamentary elections as scheduled on 8 January "looks impossible".
But Kanwar Dilshad said the final decision would be reached on Wednesday after consulting political parties.
The main opposition parties want the poll to go ahead as planned.
The campaign was thrown into doubt by the assassination of the opposition leader, former Prime Minister Benazir Bhutto, and the violence that followed.
Mr Dilshad told reporters that violent protests had directly affected the organisation of the poll in some parts of the country.
"We will inform the political parties about the situation in Sindh where our 13 offices were burnt," he said.
"We will inform them about the ground realities and then we will fix a date in consultation with them."
But opposition parties were quick to condemn any delay as a desperate measure to avoid defeat by the governing pro-Musharraf party.
"There are no grounds whatsoever for delaying the elections," said Raza Rabbani, deputy secretary general of Ms Bhutto's party, the PPP.
"It is being done only at the behest of the PML-Q as they are seeing their defeat," he said.
The other main opposition leader, former PM Nawaz Sharif, vowed his party would "agitate" against a delay.
The ruling PML-Q party has said the 8 January vote should be delayed for several weeks, on the grounds that the vote would "lose credibility" if held under current conditions.
On Monday US State Department spokesman Tom Casey said Washington wanted elections to go ahead as planned if they could be held in a "safe and secure" way.
Mr Sharif said his party would not accept the expected postponement.
Mr Dilshad said some electoral offices have been wrecked
He told a news conference that President Pervez Musharraf was a "one-man calamity" and should step down immediately.
Ms Bhutto's husband Asif Ali Zardari, who has been nominated co-chair of the PPP along with their son, Bilawal, also said the elections should go ahead as planned.
"There can be elections in Afghanistan when there is an al-Qaeda movement. Why can't there be elections in Pakistan and on time?" he asked in an interview with CNN.
Bilawal Bhutto has returned to the family home in Dubai after succeeding his mother as head of the PPP two days earlier.
PPP senator Babar Awan warned of dire consequences if the vote was postponed.
"If elections are delayed, the constitution is violated, then this would amount (to an) opening of a floodgate of violence throughout the country," he said.
At least 47 people have been killed in violence since Ms Bhutto's death.
But correspondents say that life has been returning to normal in much of Pakistan, with many shops and offices re-opening.
PPP TOP LEADERS
Asif Ali Zardari Benazir's widower and former political ally, has faced corruption and other charges
Bilawal Bhutto (pictured) Benazir's son, a 19-year-old Oxford University student, considered too young by some PPP members
Makhdoom Amin Fahim Senior PPP figure and top aide to Benazir
The BBC's Chris Morris in Islamabad says the PPP wants elections as soon as possible, in order to take advantage of what could be a big sympathy vote.
The electoral commission has asked each of Pakistan's four provincial governments to compile reports on their readiness for an election.
At least 10 local election offices have been burnt down in the rioting which followed Benazir Bhutto's death.
Ballot boxes and voting screens have been destroyed and the printing of ballot papers - and their delivery around the country - has also been disrupted.
If the election does go ahead, it is not clear who the PPP would propose as prime minister.
At 19, Bilawal is legally too young to stand for parliament.
And his father has been repeatedly accused of corruption - though he denies the charges and has never been convicted in court.
Mr Zardari said PPP vice-chairman Makhdoom Amin Fahim would probably be its candidate for prime minister.