The death toll in a massive homicide blast in Pakistan's militant-plagued northwest reached 35, officials said Sunday, as the country prepared for Benazir Bhutto's widower to take over as president.

The attack Saturday demonstrated the severe militant threat facing the Muslim nation and President-elect Asif Ali Zardari, who overwhelmingly won lawmakers' votes the same day as the blast and was expected to be sworn in by Tuesday.

Zardari has vowed to be tough on militancy, a stance that plays well in Washington, where U.S. officials worried about rising violence in neighboring Afghanistan have pushed Pakistan to clamp down on extremist havens in its borders.

Nonetheless, Zardari has a fine line to walk. Coming down too hard on insurgent activity risks inflaming Pakistani public opinion and even a tribal uprising.

At the same time, he faces pressure from opponents to reduce the powers of the presidency, something he and his party have vowed to do without specifying the extent.

Ahsan Iqbal, a spokesman for the chief opposition party, told Dawn News Television that Zardari's election was a stop on the way to restoring full democracy in Pakistan, and that the transition required giving up some presidential powers.

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.

Dozens were wounded in Saturday's attack, in which an explosives-packed pickup truck blew up at a police checkpoint on the outskirts of Peshawar, the capital of the North West Frontier Province.

Police said the large amount of explosives indicates that the bomb may have been intended for a more important target.

Television footage showed a blast crater 3 feet deep, destroyed vehicles and pieces of debris scattered across a large area. Some buildings in a nearby market collapsed, leading civilians to dig frantically with their hands to find survivors.

A teacher and school guard were among the five dead newly recovered from the rubble, police official Rashid Khan said.

On Sunday, the Election Commission said Zardari's win had been certified. His aides said he could be sworn in within a couple of days.

Newspaper editorials marking Zardari's ascent noted that a recent U.S.-led ground assault in a Pakistani tribal region along the Afghan border signaled American impatience with Pakistan's progress in battling insurgents.

Far from being confident, however, the opinion pieces warned that Zardari is yet unproven and still tainted by a history of corruption allegations.

"What Mr. Zardari needs to do is to dispel the impression that he is a political wheeler-dealer who is adept at making backroom deals but unable to rise to the requirements of statesmanship," said an editorial in Dawn, a leading Pakistani English-language paper.