ISLAMABAD, Pakistan — Lawmakers in Pakistan's most powerful province on Monday accused President Pervez Musharraf of gross misconduct and demanded he step down, an opening salvo in the ruling coalition's campaign to oust the defiant former army chief.

The political battle unfolded as witnesses reported Pakistan's military rained bombs on militants in a tribal region along the border with Afghanistan in fighting that has killed dozens of people and forced thousands to flee in recent days.

The events underscored the volatility in Pakistan, a politically and economically struggling country whose help is seen by Washington as critical to winning the war on extremist groups.

Legislators in Punjab province's assembly voted overwhelmingly, 321-25, for the anti-Musharraf resolution, even drawing support from 35 members of the main pro-Musharraf party, the Pakistan Muslim League-Q.

Lawmakers from the national governing coalition chanted "Go, Musharraf, go!" and stood in support for the resolution, which called the longtime U.S. ally "unfit" to serve and accused him of violating the constitution, gross misconduct and economic mismanagement.

Though the measure carries no constitutional weight, it ramps up the pressure on the president.

Musharraf seized power in a 1999 military coup and dominated Pakistan for years, but he grew increasingly unpopular, especially after he removed dozens of judges and declared emergency rule last year. He has been largely sidelined since his foes won February's parliamentary elections.

The resolution calls on Musharraf to seek a vote of confidence by the federal and provincial assemblies or to resign. Otherwise the Punjab assembly will ask Parliament to impeach him.

The other three provincial assemblies are expected to vote on similar resolutions in the coming days, after which an impeachment motion would be brought up in Parliament.

Chaudhry Pervez Elahi, leader of the pro-Musharraf bloc in the National Assembly, predicted any impeachment process would take months and involve many twists. He said his party would stand by the president.

"We will defend him in every form," Elahi said.

Khawaja Asif, a top official in one of the governing coalition parties, predicted the upcoming provincial assembly votes will produce similar results to that in Punjab.

"I personally feel that Musharraf's goose is cooked," Asif said. "Nobody wants to be in a sinking ship. They want to be on the right side at this crucial moment."

No president has been impeached in Pakistan's turbulent 61-year history, but the coalition argues it will succeed in getting the two-thirds majority required in a joint sitting of both houses of Parliament to strip Musharraf of the presidency.

Analysts say a vote to oust Musharraf could be close. The president also retains the right to dismiss Parliament and the prime minister, but such moves would be highly controversial and require support from the army, which has indicated it wants to stay out of politics.

In a statement Monday, the U.S. Embassy signaled that Washington is concerned about maintaining favor with Pakistan's new leaders whatever happens to Musharraf.

"We remain close allies in the war on terror and will continue our close ties with the democratically elected government of Pakistan," embassy spokesman Lou Fintor said.

Pakistan is under intense American pressure to root out Islamic militants in its tribal regions on the Afghan frontier — areas that are considered havens for insurgents attacking U.S. and NATO forces across the border in Afghanistan.

On Monday, Pakistani military forces dropped bombs and shot at suspected militant positions as part of an offensive that began last week in Bajur tribal region, witnesses said.

The army spokesman, Maj. Gen. Athar Abbas, said authorities were checking reports a close aide of al-Qaida No. 2 leader Ayman al-Zawahri was killed, but declined to comment otherwise on the operation. Bajur is considered a possible hiding place for al-Zawahri and Osama bin Laden.

Officials have reported at least 100 militants and nine paramilitary troops killed in the dayslong fighting. Witnesses said aerial bombardments Sunday and Monday killed at least 13 people, but it was unclear who all the victims were.

Witnesses and local media said thousands had fled villages. About 200 people, many of them women and children, waited at the main bus stand of Khar as darkness fell Monday.

"I took the risk and came out of twice-bombed Mamund because, even though we were spared in the bombing, we may starve as no supply is coming up there," said Muhammad Din, who at times carried his elderly mother on his back.