( AP ) - Former Prime Minister Nawaz Sharif returned from exile Sunday to an ecstatic welcome from thousands of supporters and immediately stepped up the pressure on U.S.-backed military ruler Gen. Pervez Musharraf to end emergency rule.
The arrival of one of Musharraf's harshest critics was a fresh challenge for the president, who has faced intense domestic and international condemnation since he declared a state of emergency on Nov. 3, locking up thousands of opponents, purging the Supreme Court and muzzling the media.
Sharif, who was ousted by Musharraf in a 1999 coup, planned to register for crucial Jan. 8 elections by a Monday deadline. But he also threatened to boycott the vote if Musharraf does not end emergency rule. An opposition boycott could deal a potentially fatal blow to the president, who has claimed Pakistan is heading toward democracy.
"Musharraf has taken this country to the brink of destruction," Sharif told crowds of supporters and onlookers from the top of a truck carrying him from the airport into his home city of Lahore.
"When the constitution, fundamental rights are suspended, when people live difficult lives, when judges who make decisions according to the constitution are ousted, will elections in such a situation not be a fraud?" he said.
"Should not such elections be boycotted?" Sharif asked, prompting chants of "boycott, boycott!"
He arrived from Saudi Arabia, where has spent most of his eight years in exile.
Musharraf swiftly booted Sharif back to the kingdom when he flew into Pakistan in September. But the Pakistani leader appears to have lost the support of the Saudi royal family, who provided a special flight to carry Sharif and a host of his relatives home.
Sharif had to fight his way through a crush of wildly cheering supporters outside the airport terminal. He looked composed as he insisted that his return was "not the result of any deal" with Musharraf.
A car carrying Sharif left the airport in a snail-paced procession toward a shrine in the center of the city, surrounded by supporters waving the green flags of his party and chanting "Musharraf go!"
Police had deployed some 5,000 officers in an attempt to prevent chaos at the airport and protect Sharif from the fate of Bhutto, whose homecoming was wrecked by a suicide bombing that killed about 150 people.
Sharif's party has said he and his brother will file their papers before Monday's deadline for nominations for the Jan. 8 vote.
Bhutto filed her nomination papers on Sunday, but both former premiers say a broad opposition coalition could still decide to boycott if Musharraf does not take steps to ensure the election is fair.
Equally tricky for Musharraf would be an alliance between Sharif and Bhutto. Washington had been coaxing Bhutto toward an alliance with the embattled dictator until the emergency threw Pakistani politics into confusion.
Bhutto welcomed Sharif's surprise return and did not rule out an election alliance with her former political foe.
"If they come to us with a proposal of any electoral alliance, we will consider this positively," she told The Associated Press on Sunday aboard a flight from Karachi to her hometown of Larkana, in southern Pakistan. "I welcome him home."
Musharraf is moving quickly to ease some of the restrictions he imposed under the emergency and to belatedly make good on a pledge to end military rule. He is expected to step down as army chief within days and take a new oath as a civilian head of state.
Most of the thousands of opponents, human rights activists and lawyers detained since Nov. 3 have been released.
But Musharraf has so far resisted strong pressure from the United States - his biggest foreign ally - to lift the emergency and restore the constitution.
Talat Masood, a prominent Pakistani political analyst, said Sharif's comeback could energize opposition parties and force Musharraf to quickly lift the emergency.
He said Sharif could profit in the polls from having a cleaner image than Bhutto, whom many Pakistanis view as corrupt.
"She gives the impression that she is being dictated to by the West, that she wanted to compromise with Musharraf. That has lowered her image a bit," Masood said.
Sharif and Musharraf have been bitter foes since the former prime minister tried in 1999 to fire the general - his hand-picked army chief - provoking the coup.
A court convicted Sharif of hijacking and terrorism for trying to prevent a plane carrying Musharraf back from a foreign trip from landing in Pakistan, despite a shortage of fuel.
A year later, Sharif agreed to go into exile for 10 years to avoid a life sentence in prison.
Despite the animosity, the pro-Musharraf ruling party PML-Q was already wooing Sharif as a potential ally. Spokesman Tariq Azim, spokesman urged Sharif's camp to "forget the old egos and start with a clean slate."
But Khawaja Mohammed Asif, a senior member of Sharif's party, rejected the overture, saying PML-Q would crumble with Musharraf's exit.
Musharraf has cited rising religious extremism as a reason for the emergency, though many of those targeted have been opponents, lawyers and members of the media.
On Saturday, suicide bombers killed up to 35 people in nearly simultaneous blasts in Rawalpindi, a garrison city adjacent to Islamabad.
The army said Sunday that more than 30 pro-Taliban fighters and two Pakistani soldiers died in clashes in the Swat valley, about 100 miles from Islamabad.