Unofficial results announced after separate votes in the federal and provincial assemblies showed Asif Ali Zardari won an overwhelming majority, bolstered by public loyalty to his late wife and hopes that he can pull the country out of its economic doldrums.
Pro-Zardari lawmakers, some in tears, shouted "Long live Bhutto!" as the vote tallies came in. The couple's two jubilant but tearful daughters, one carrying a portrait of their late mother, smiled and hugged friends in the gallery of the National Assembly.
But Saturday also brought a brutal reminder of the threats to the nuclear-armed nation's stability as a suicide car bomber killed at least 17 people and wounded dozens near the northwestern city of Peshawar.
The blast destroyed a police checkpoint and collapsed several nearby shops. Civilians dug frantically with their hands for possible survivors.
Head of the main ruling party, Zardari becomes one of the most powerful civilian leaders in Pakistan's turbulent 61-year history. Last month, he marshaled a coalition that forced longtime U.S. ally Pervez Musharraf to quit as head of state.
Zardari, a novice leader untested on the international stage and stained by past corruption allegations, takes over at a critical time for the volatile Muslim nation of more than 160 million.
The economy is crumbling, and Saturday's attack was the latest in a string of suicide bombings usually claimed by Islamic militants who have steadily gained strength since Pakistan joined the U.S. war on terrorism in 2001.
On Saturday evening, Zardari hugged and shook hands with supporters and well-wishers who attended a celebratory dinner in the gardens of the prime minister's residence on a hill overlooking the capital.
In a brief speech, he rejected criticism that he would be a divisive president and took another swipe at Musharraf, a former general.
"To those who would say that the People's Party or the presidency would be controversial under our guardianship, under our stewardship, I would say listen to democracy," he said.
Echoing one of his late wife's favorite slogans, he said "democracy was the best revenge" against military rulers.
Washington is pressing Pakistan hard to eradicate Taliban and al Qaeda havens near its border with Afghanistan. An American-led ground attack, said to have killed at least 15 in Pakistani territory Wednesday, sparked outrage and embarrassed Zardari's party.
The U.S. government congratulated Zardari. Secretary of State Condoleezza Rice, who has not met Zardari but has spoken with him by phone, said she looked forward to working with him.
"I've been impressed by some of the things he has said about the challenges that Pakistan faces, about the centrality of fighting terrorism, about the fact that the terrorism fight is Pakistan's fight and also his very strong words of friendship and alliance with the United States," Rice said.
Tariq Raza, a 45-year-old teacher in the central city of Multan, called Zardari's victory a last chance for his party to prove it can improve the economy and fight terrorism.
"The PPP is in power just because of the sympathy vote after the brutal murder of Benazir Bhutto," Raza said. "We want him to save Pakistan from becoming Iraq and Afghanistan."
Musharraf, who seized power in a 1999 military coup, yielded his army post last year after imposing a state of emergency to fend off legal challenges to winning another term, this time as a civilian head of state.
Zardari says he will relinquish some of the powers accumulated by Musharraf but has not made clear how far he will go, sustaining concern that one strongman is replacing another.
Interior Ministry chief Rehman Malik said Saturday's bombing was an attempt to upset the progress of a country riven by ethnic and sectarian divides toward a more stable democracy.
If a reported Taliban claim of responsibility proves correct, "They'll have to pay for it," he said.
Like his late wife, Zardari is generally considered a pro-West liberal. He is not expected to change Musharraf's commitment to the U.S. war on terrorism, insisting the battle against militants is Pakistan's own war. But a key test will be how much clout Zardari wields over the powerful military, which has failed to halt the Taliban's rise in the volatile northwest.
The president has the power to dissolve Parliament and appoint army chiefs, and chairs the joint civilian-military committee that controls Pakistan's nuclear weapons.
Zardari, who has spent about 11 years in prison on corruption allegations but was never convicted, has surprised many with his ability to concentrate power since his wife was killed in a December gun-and-bomb attack and he inherited her party's leadership.
After ex-Prime Minister Nawaz Sharif's party switched to the opposition last month, Zardari quickly won support from smaller parties, suggesting he could provide some stability as the country faces soaring inflation, power shortages and widening trade and budget deficits.
Saturday's voting bore that out.
A tally of the unofficial results showed Zardari with 488 of the 685 votes, based on a formula that gave each of the four provincial assemblies equal representation and left most of the say with federal lawmakers.
Saeed-uz-Zaman Siddiqui, a former judge nominated by Sharif's party, was second with 153. Mushahid Hussain, a senator from the pro-Musharraf party routed in February parliamentary elections, was last with 44.
The Election Commission was expected to certify the results later Saturday.
Zardari, the son of a landowning businessman and tribal chief from the southern province of Sindh, wed Bhutto in an arranged marriage in 1987. Many Pakistanis call him "Mr. 10 Percent," a reference to accusations he pocketed commissions on government contracts during her two terms as prime minister.
After Bhutto was killed, Zardari returned to Pakistan from exile, seized the reins of her party and led it to victory in the February elections.
Although Zardari has emerged as a powerful ruler for Pakistan, his campaign was targeted by opponents who referred to his past image for allegedly being involved in corruption.
The late Ms Bhutto's government was dismissed twice, in 1990 and 1996, on issues including alleged corruption involving her husband.
Western diplomats said Zardari will have to move quickly to oversee at least some progress in taking on difficult challenges facing Pakistan, notably in fighting militants and reviving an increasingly troubled economy.
"Asif Zardari will have no room to make mistakes" said the Western diplomat who spoke to CBS News.
Blast, Clashes In Northwest Pakistan Kill 41
A pickup truck packed with explosives blew up a security checkpoint Saturday in northwestern Pakistan, killing at least 17 people and injuring 80 in an attack possibly intended for a more important target, officials said.
About 100 miles away in the volatile region, 24 people were killed after residents of villages tired of a "reign of terror" by Islamic militants foiled a militant kidnap attempt, then were attacked, the military said.
The suicide attack occurred on the outskirts of Peshawar. Television footage showed a blast crater three feet deep and destroyed vehicles and pieces of debris scattered across a large area. Officials said many people were trapped under the rubble of damaged buildings in a nearby market. Civilians dug frantically with their hands in hopes of finding survivors.
Nasirulmulk Bangash, a top police official in the area, said the vehicle carried at least 330 pounds of explosives - an amount he called "unprecedented" - and was apparently en route to Peshawar, the capital of the North West Frontier Province.
The amount of explosives indicated the attack was aimed at a higher-value target than the small checkpoint, but might have been tripped up by high security on election day, Bangash said, without speculating on what the intended target might have been.
At least 17 people died and about 80 were wounded, including 15 who were in critical condition, said Sahib Gul, an official at Lady Reading Hospital in Peshawar. Several of the dead were believed to be police manning the post.
Sher Zaman, 15, told The Associated Press from a hospital bed that he was selling fruit from a cart at the market when he heard a large explosion and was knocked down when something hit him in the chest. He said residents quickly gathered and helped transport casualties to hospitals.
No one immediately claimed responsibility for Saturday's blast.
A senior intelligence official speaking to CBS News from Peshawar, capital of the North West Frontier Province (NWFP), said the attack appeared to have been carried out by the Taliban movement, which has backed a fast-growing number of violent attacks in the past year.
This was the first attack since Wednesday, when Pakistani officials accused Afghanistan-based U.S. commandoes of carrying out a raid in a village on Pakistan's territory along the Afghan border.
In retaliation for that attack, late Friday evening, Pakistani officials ordered all supplies for NATO and U.S. troops heading in to Afghanistan to be stopped, prompting fresh anxiety among Western diplomats.
"Even if these supplies resume after discussions between U.S. and Pakistani officials, there is a very powerful message which is, there is ground for discord in U.S.-Pakistan relations" said one Western diplomat in Islamabad who spoke to CBS News on condition of anonymity.
A military statement also said residents of the town of Tehsil Matta, some 100 miles north of Peshawar, decided to fight back against militants operating in the area. They launched an
attack Friday night to prevent a suspected plan to snatch a village elder accused of supporting the government.
Six of the would-be kidnappers were killed. The militants later returned en masse, and ensuing clashes left 15 residents and three more militants dead, along with scores of people injured, the military said.