ISLAMABAD, Pakistan—A deadly American-led raid on a Pakistani village embarrassed the government and eroded support for the pro-U.S. presidential front-runner Thursday just two days before the election.

Furor continued to mount over the first known foreign ground assault inside Pakistan against a suspected Taliban haven. The government summoned the U.S. ambassador for an official protest, while Parliament passed resolutions of condemnation.

In news likely to stoke more anger, intelligence officials said a missile strike was suspected in a blast Thursday that killed at least four people in North Waziristan, part of the tribal belt where Osama bin Laden and his deputy are thought to be hiding. Previous such strikes have been blamed on the U.S.

The ground assault, with troops helicoptered in, occurred in adjacent South Waziristan early Wednesday. Officials said at least 15 people died, including women and children. The Foreign Ministry said no militant leaders were killed and there was no sign the attackers detained anyone.

U.S. officials declined public comment. But a U.S. military official said intelligence had indicated the presence in the village of people “clearly associated with attacks on U.S. forces in Afghanistan.” He spoke on condition of anonymity because of the sensitivity of cross-border operations.

The raid has complicated life for presidential front-runner Asif Ali Zardari and his governing Pakistan People’s Party heading into Saturday’s vote by legislators to elect a successor to former President Pervez Musharraf, who resigned under pressure last month.

The party, which came to power after defeating Musharraf’s allies in February, is generally supportive of Washington’s war on terrorism. But it has to tread carefully because many Pakistanis blame the alliance for fueling violence by Islamic militants in their country.

Still, the party has tried to convince Pakistanis they cannot duck the fight.

In a column published Thursday in The Washington Post, Zardari, widower of slain former prime minister Benazir Bhutto, said Pakistan is committed to fighting terrorist groups.

“We stand with the United States, Britain, Spain and others who have been attacked,” wrote Zardari, whose wife was assassinated in a gun-and-bomb attack last December. “Fundamentally, however, the war we are fighting is our war. This battle is for Pakistan’s soul.

“I will work to defeat the domestic Taliban insurgency and to ensure that Pakistani territory is not used to launch terrorist attacks on our neighbors or on NATO forces in Afghanistan.”

The cross-border raid has cut into support for Zardari’s presidential bid.

The leader of a group of lawmakers from the tribal areas along the Afghan border, Munir Khan Orakzai, said they would not vote for Zardari, calling the attack evidence that the new government has failed to bring peace to their troubled region.

Zafar Ali Shah, a lawmaker from the chief opposition party of ex-prime minister Nawaz Sharif, said Pakistan should tell America: “Enough is enough, and we will not help you if you kill our people. The American war against terrorism has become a war against Pakistan.”

A People’s Party spokesman, Farhatullah Babar, acknowledged the attack embarrassed the government and said it threatens to undermine joint efforts with the West. He said Zardari condemned the attack and wanted compensation paid to the victims.

“We have been very clear that any action on this side of the border must be taken by the Pakistani forces themselves,” Babar said. “It is very embarrassing for the government. The people will start blaming the government of Pakistan.”