The party of assassinated Pakistani opposition leader Benazir Bhutto is meeting to discuss a successor and whether to contest imminent elections.
Mr Zardari said his wife's successor would be the PPP's decision
Members of the Pakistan People's Party gathered at Ms Bhutto's family home in Larkana to hear her political will, which could name her choice for leader.
Correspondents say her husband, Asif Ali Zardari, is a possible contender.
However, elections due on 8 January were "likely" to be delayed for several weeks, a ruling party official said.
It comes amid unrest following Ms Bhutto's assassination, in which at least 38 people have died, disarray in her party, one of Pakistan's largest, and a threat by other parties to boycott the poll.
Troops have been deployed in several main cities after two days of rioting and looting left hundreds of shops and vehicles, along with several election offices, in ruins, while roads have been deserted and businesses shut.
President Pervez Musharraf ordered firm action to crack down on the violence that has broken out since Ms Bhutto was killed after attending an election rally in Rawalpindi on Thursday.
There was what appeared to be another attempted assassination of a top politician on Sunday.
Police said two suicide bombers blew themselves up - perhaps prematurely - near a house where Muhammad Ejaz-ul-Haq, a former religious affairs minister, had been staying in the southern Punjab. Apart from the bombers, no-one was hurt.
In the midst of the unrest, Ms Bhutto's Pakistan People's Party (PPP) is also said to be in disarray about who will succeed her as leader and what it should do.
The Central Executive Committee opened a meeting in her home town of Naudero, in the Larkana district in the southern province of Sindh, on Sunday to debate such matters and to hear her 19-year-old son, Bilawal, read out a political will she left that detailed her views on the PPP's future.
Pakistani media picked out two suspected attackers, one of which apparently raised a gun (bottom)
Thousands of Bhutto supporters surrounded the estate ahead of the meeting, venting their anger with chants like: "Curse on Musharraf, Musharraf is a killer".
Ms Bhutto's widower, Asif Ali Zardari, told the crowd that "Benazir Bhutto sacrificed her life for Pakistan's survival and democracy. We will continue Bhutto's mission."
There is increasing speculation that Mr Zardari will be named as the person the late leader wanted to take over the party, but the long-time vice-chairman, Makhdoom Amin Fahim, is also believed to be an option.
Asked whether he wanted to lead the PPP, Mr Zardari told the BBC that would be "the party's decision".
"It depends on the party and it depends on the will," he said on Saturday.
Mr Zardari played a prominent role in both his wife's administrations during the 1980s and 90s. He was freed on bail in November 2004 after spending eight years in prison in Pakistan on charges ranging from corruption to murder.
The PPP leadership must also decide whether to contest the parliamentary election scheduled for 8 January amidst such instability.
Earlier, a former Pakistani attorney-general and member of the Pakistan People's Party, Iqbal Haider, told the BBC that the vote had to be postponed, echoing the view of Ms Bhutto's former rival, Nawaz Sharif.
Some opposition politicians also want a new caretaker government to organise the elections. They claim the one in place favours supporters of President Musharraf.
Pakistan's election commission has meanwhile called an emergency meeting on Monday to discuss the impact of the assassination on its plans.
The meeting in Naudero also comes amid growing controversy surrounding Ms Bhutto's death, with the government, her party and independent witnesses all giving differing accounts.
Overnight, local television released new pictures it said showed her two attackers, a gunman and a suicide bomber, and another showing Ms Bhutto was inside the car, and no longer standing through the sun roof, when the explosion happened.
The BBC's Barbara Plett in Islamabad says that the images cast further doubt on the government's explanation of how Miss Bhutto died.
Interior ministry spokesman Brig Javed Iqbal Cheema said on Friday that she was killed when the force of the bomb blast knocked her head against a sun roof fitting, and was not hit by bullets.
A surgeon who treated her, Dr Mussadiq Khan, said earlier that she may have died from a shrapnel wound, while the PPP has insisted she was killed by two bullets, one of which pierced her skull and another which hit her in the neck.
The government has repeated its accusation that a Pakistani militant, Baitullah Mehsud, ordered her assassination.
The tribal leader from South Waziristan, who has close links to al-Qaeda, has denied the accusations through a spokesman.