The action was a first in a country where the powerful military has regularly ousted civilian governments, either directly through coups or indirectly through constitutional maneuvers, and it offered hope that the parliamentary system was maturing.
Still, a faltering economy and widespread militant violence have left many Pakistanis grumbling about the lack of tangible dividends from democracy, and the governing Pakistan Peoples Party, whose governance record has faced stiff criticism, will face a strong challenge from the opposition leader, the former Prime Minister Nawaz Sharif.
A peaceful transfer of power would be a political victory of sorts for President Asif Ali Zardari, who has confounded regular predictions of the demise of his government over the past five years. A good showing by his party may help him win re-election when his terms expires next September. (Pakistan’s president is indirectly elected by the national and regional assemblies).
Prime Minister Raja Pervez Ashraf was due to address the nation by television on Saturday night, when he will announce the date of the vote — expected for early May — and may announce the head of a caretaker administration to run the country in the interim.
Recent polls indicate that the party of Mr. Sharif, who was ousted in a military coup in 1999, is the favorite to win the vote. A Gallup poll in February gave his party 27 percent support, with the Pakistan Peoples Party running a distant second. Since analysts say he is unlikely to muster an outright majority, a range of ethnic, regional and religious parties could hold the balance of power in determining a coalition government.
Other personalities and factors are also expected to play a role. The cricketer-turned-politician Imran Khan, who has campaigned heavily against corruption and in opposition to American drone strikes, hopes to eat into Mr. Sharif’s support base in Punjab Province, which accounts for over half of the 272 elected seats in Parliament.
The former military ruler, Gen. Pervez Musharraf, has vowed to return from exile on March 24 to contest the election, even though he faces criminal prosecution in court cases related to his rule between 1999 and 2008.
And Muhammad Tahir-ul Qadri, a charismatic preacher who led thousands of supporters into central Islamabad for a protracted sit-in last January, says he will help ensure the integrity of the election.
In a crucial development, the army chief, Gen. Ashfaq Parvez Kayani, has emphasized that he fully supports the elections, and there are few indications that the military is backing any one party. “The military is apparently standing aloof and letting the battle be fought among politicians, which is a rare thing and a healthy one,” said Ahmed Bilal Mehboob, of the Pakistan Institute of Legislative Development and Transparency.
The often stormy relationship between Pakistan and the United States has been relatively placid in recent months, although widespread public hostility toward Washington may be mobilized for political gain.
Last week, Mr. Zardari and President Mahmoud Ahmadinejad of Iran held a ceremony to commemorate the start of construction in Pakistan of a gas pipeline between the two countries, which has been bitterly opposed by the Obama administration and could, if completed, lead to economic sanctions against Pakistan.
Analysts, however, say the pipeline will take years to complete, and the ceremony may have been dictated by political considerations.
“Perceived or real defiance of American power is perceived to be a plus in Pakistan,” Mr. Mehboob said.
The political system last week was gripped by speculation about the identity of the caretaker prime minister, who will lead an interim administration in the prelude to the elections.
The government and opposition were deadlocked over the nomination of the caretaker prime minister on Saturday.