ISLAMABAD, PAKISTAN — The resignation of President Pervez Musharraf will force Pakistan's untested new civilian government to confront a dizzying array of problems, chief among them an intensifying battle against Islamic insurgents in the nation's long-lawless tribal areas.
Musharraf's departure Monday, greeted with near-delirious rejoicing in the streets of Pakistani cities, also opens the door to a potentially debilitating power struggle within the country's fragile ruling coalition, which was bound together mainly by its anti-Musharraf stance.
Nuclear-armed Pakistan, perhaps the most important yet most troubled U.S. ally in the fight against Al Qaeda and the Taliban, enters an uncertain new era with the departure of Musharraf, who stepped down hours before a parliamentary session that was to have been a prelude to impeachment proceedings over his alleged constitutional violations.
Bush administration officials had kind words Monday for the departing president, whom they had continued to support publicly long after the Pakistani public grew disenchanted with him. Musharraf, said Secretary of State Condoleezza Rice, "has been a friend to the United States and one of the world's most committed partners in the war against terrorism and extremism."
Lately, though, his American patrons had made clear their own growing disenchantment as billions of dollars in military aid yielded few visible results in the effort against militants. After having placed so much faith in Musharraf, the administration has recently been trying to cultivate a much broader range of relationships in Pakistan -- with civilian politicians, military leaders and intelligence officers.
After months of posturing and saber rattling by Musharraf and his political foes and days of tense back-channel negotiations, the end for the 65-year-old president was astonishingly swift.
In the span of a few hours, Musharraf delivered his resignation speech for the cameras, saluted a high-stepping honor guard and climbed into a shiny black limousine, leaving the presidential palace for perhaps the last time.
The competition to succeed him could prove bitter and divisive.
As stipulated by the constitution, the chairman of the Senate, Mohammedmian Soomro, immediately took over as acting president. A new president is to be selected by lawmakers within 30 days, and the choice may be far from unanimous.
The Pakistan People's Party, the senior partner in the 5-month-old ruling coalition, said there was no doubt that the new president would come from its ranks. The party's ceremonial head, Bilawal Bhutto Zardari -- the college-age son of assassinated former Prime Minister Benazir Bhutto -- flew to the port city of Karachi and declared there would be a PPP president.
"Democracy is the best revenge," the Oxford student said, smiling as he quoted his mother, who was slain in December.
But a candidacy by his father, Asif Ali Zardari, the leader of the PPP, could prove highly problematic.
Many Pakistanis vividly remember Zardari's corruption-tainted tenure as a Cabinet minister in the 1990s, when he was known as "Mr. 10%" for the kickbacks he allegedly demanded.
The PPP has suggested the new president might be a woman, which could pave the way for the respected new speaker of parliament, Fehmida Mirza, who bears an uncanny resemblance to the late Bhutto.
Another possible candidate is the new prime minister, Yusaf Raza Gillani, who spent years in jail under Musharraf.
However, the head of the junior party in the ruling coalition, former Prime Minister Nawaz Sharif, could also assert a claim to the presidency. Without his insistent demands that Musharraf be ousted, the PPP would probably have been content to allow the president to serve out his term as a figurehead.
One question is how much power the new chief executive will have.
Musharraf's authority had waned dramatically in recent months, first when he relinquished his army chief of staff post in November and again when his party suffered crushing defeat in parliamentary elections six months to the day before he resigned.
But during his nearly nine years in office, Musharraf worked assiduously to strengthen the powers of the presidency. The ruling coalition had been preparing a package of reforms aimed at reversing some of those moves, although the PPP may now resist enacting them.
In his speech, Musharraf said he had asked for no concessions in exchange for his resignation, although intense indirect negotiations had been underway for days in an effort to secure a promise of legal immunity for him.