Five days after the suicide bombing that killed at least 136 at her homecoming procession in Karachi, Bhutto said her lawyer received a letter from an unidentified "friend of al Qaeda" threatening to slaughter her "like a goat."
Bhutto said the letter was addressed to her lawyer, Farooq Naik, and had been left for him at the Supreme Court in Islamabad. She said Naik was alerting the chief justice of the threat.
"There are elements who want who to kill us," Bhutto said at her heavily guarded residence in this southern city. "They are petrified that the Pakistan People's Party will return (to power) and that democracy will return."
"They are trying to derail the democratic process because they know if the people are employed and educated the forces of extremism and terrorism will be weakened," she said.
The authenticity of the letter could not be confirmed. Bhutto said the writer claimed to be the "head of the suicide bombers and a friend of al Qaeda and Osama bin Laden."
Bhutto returned Thursday from eight years in exile to campaign for parliamentary elections due in January, after months of talks with President Gen. Pervez Musharraf that could see them working side-by-side in the next government.
She said that after discussions, her party had decided she should avoid staging mass rallies because of the risk of suicide and roadside bombings, but would still address public meetings.
"The party decided I should go from Karachi to Islamabad, Lahore or Larkana (Bhutto's hometown) in the next couple of days. We will be not be holding public rallies but will be traveling to meet the people in other provinces," she said.
Bhutto has blamed alleged extremist elements in the government and the security apparatus for the bombing that ripped through Thursday's rally in Karachi - claims the government denies.
"I think that sympathizers of al Qaeda and extremist militants in the security administration were responsible for trying to kill me," Bhutto said Monday on CBS News' The Early Show. "I would like an independent inquiry conducted by the government of Pakistan and assisted by the international community, which has expertise in terrorism-related matters, to clarify, inquire, and find out who the culprits were."
She alleges they include remnants of the regime of former military leader Gen. Zia-ul Haq, who oversaw mujahedeen groups that fought the Soviet occupation of Afghanistan in the 1980s, then became Taliban and al Qaeda. She alleges some members of the ruling party, including its chief, were behind Thursday's attack.
That has raised questions about how the parties could form a coalition in support of Musharraf after the elections. Although Bhutto and Musharraf are rivals, both are moderates keen to combat religious extremism. And Musharraf has signed an amnesty to quash graft cases against Bhutto.
Bhutto's party has said she is on a list of people who are not allowed to leave the country, but local media reports say that is not the case.
Railways Minister Sheikh Rashid Ahmed, a close Musharraf aide, predicted Tuesday that the People's Party would be part of the next government. "There is good understanding between Gen. Pervez Musharraf and Benazir Bhutto," he said.
He said there is "nothing of this sort" between her party and the ruling Pakistan Muslim League-Q but maintained they were both likely to be part of the next coalition. He forecast they would be joined by the Islamist Jamiat Ulema-e-Islam party - whose deputy leader met with Bhutto on Tuesday.
However, Ahmed said he did not expect Bhutto to become prime minister for a third time.
Bhutto's two governments between 1988 and 1996 were toppled amid allegations of corruption and mismanagement. There is a ban on a premier serving more than two terms, but she remains determined to secure the position, possibly through a constitutional amendment.
Bhutto also escalated her scathing criticism of ruling party leader Chaudhry Shujaat Hussain, who in an apparently sarcastic response to her claim that he is plotting to kill her, on Monday accused Bhutto's husband of arranging the blasts to stir up public sympathy.
Bhutto called that a "lunatic statement" and claimed Hussain objected to Pakistan seeking international assistance in the investigation because he wanted to "cover up this heinous terrorist attack."
Sindh provincial Gov. Ishrat Ul-Ebad Khan said Tuesday that two suicide bombers - not one as earlier believed - carried out the attack. He said the state agency that oversees Pakistan's national identity cards was helping to try to identify the bombers, one of whose pictures has been made public.