ISLAMABAD, PAKISTAN - Pakistan's federal minorities minister, a Christian, was gunned down by suspected Islamist militants in this capital city Wednesday in the second killing this year of a senior government official who had spoken out against the country's stringent anti-blasphemy laws.

Shahbaz Bhatti, the sole Christian cabinet member in majority-Muslim Pakistan, was shot multiple times by gunmen who surrounded his car as he left for work from his mother's house, near his home in a residential neighborhood. The attackers fled, but fliers scattered at the scene bore the names of the militant Islamist groups Punjabi Taliban and al-Qaeda.

In Washington, President Obama said Bhatti had "most courageously challenged the blasphemy laws of Pakistan under which individuals have been prosecuted for speaking their minds or practicing their own faiths" and called on Pakistan to bring the killers to justice.

The assassination came as a severe blow to Pakistani liberals, who are increasingly being silenced by Muslim hard-liners willing to use violence against those who do not share their views. Bhatti's death removed one of the few leaders still openly advocating the reform of laws that make insulting Islam a capital crime - a stance that Prime Minister Yousaf Raza Gillani and other politicians disowned after the governor of Punjab province was killed in January.

The governor, Salman Taseer, had also argued for changes to the laws, which he and Bhatti said were used as tools to settle vendettas and persecute members of religious minorities. The Pakistani news media and a broad spectrum of clerics have repeatedly turned that characterization around, equating its proponents with blasphemers.

The police guard who killed Taseer has since been lauded as a hero even by Pakistan's lawyers and mainstream Muslims, exposing the broad reach here of religious conservatism and intolerance.

As they did after Taseer's assassination, government officials condemned Bhatti's killing Wednesday. Farahnaz Ispahani, a spokeswoman for President Asif Ali Zardari, said in a statement that "the time has come for the federal government and provincial governments to speak out and to take a strong stand against these murderers to save the very essence of Pakistan."

But the government, led by Zardari's Pakistan People's Party (PPP), has not championed the views of Taseer and Bhatti. Zardari and Gillani did not attend Taseer's funeral. Sherry Rehman, a ruling party lawmaker who had proposed legislation to reform the anti-blasphemy laws, withdrew the bill, saying the party did not support it. The firmest party statement against extremism after Taseer's killing came from the son of Zardari and former prime minister Benazir Bhutto, who was assassinated in 2007 - but he spoke from London.

A senior government official defended those responses as pragmatic steps taken deliberately by the party, which says it stands for liberal ideals.

"These people are trying to push us into a position to react in an open way, and when we do that, there is going to be a wholesale slaughter," the official said, referring to extremists.

Rights activists say that position amounts to an appeasement of extremists. Ali Dayan Hasan, Human Rights Watch's representative in Pakistan, said that the government must systematically arrest those who incite and praise killers in the name of religion and that the PPP needs to mobilize its large voting base to take to the streets in support of tolerance.

"This whole idea that you can effectively combat the Taliban and Talibanization without combating intolerance in Pakistani society is a big hoax," Hasan said. "There are 100 different ways of signaling large-scale support for [people such as Bhatti.] The PPP failed to engage in any of those."

Bhatti led a government investigation late last year into the case of a Christian woman sentenced to death on blasphemy charges, a penalty that drew international attention. Bhatti said at the time that he had determined she was innocent and deserved to be pardoned and that Zardari had appointed him to a committee to review the blasphemy statutes.

The fliers left at the scene of his assassination made apparent reference to that committee, saying it was formed "in support of the blasphemers" and led by "a Christian infidel, a cursed one, Shahbaz Bhatti."

In an interview last month, Bhatti declined to criticize the government for not pushing for the reforms, saying Zardari and Gillani had demonstrated their support by keeping him on as minorities affairs minister after a cabinet reshuffle. But he said he would continue to press for changes to the anti-blasphemy laws and work on interfaith initiatives.

"I can't compromise," he said. "I want to give hope for those people whose voices are under fear and threat. . . . If you look on the ground, there is no one boldly speaking out."

Bhatti said threats to his life, which he had received for years, increased after Taseer's death. One recent phone call, he said, came from someone who identified himself as a Taliban member and threatened to behead him. Bhatti said that he had requested additional security but that law enforcement authorities were "dilly-dallying."

Wajid Ali Durrani, the police chief in Islamabad, said Wednesday that Bhatti had been assigned two police squads of about five officers each to escort his vehicle but that he had chosen not to travel with them Wednesday.

Rising religious extremism has prompted concern in the United States, which has given billions of dollars to help Pakistan's military and government counter the trend.

Bhatti was well known in Washington, which he visited last month and where he met one-on-one with Secretary of State Hillary Rodham Clinton.

On Wednesday, Clinton denounced Bhatti's slaying as an attack "not only on one man, but on the values of tolerance and respect for people of all faiths and backgrounds." She said she had met Bhatti and found him to be a "very impressive, courageous man."

The U.S. ambassador to Pakistan, Cameron Munter, called Bhatti a "Pakistani patriot and a voice for understanding" who was dedicated to making his country "a beacon of democratic tolerance."

Staff writer Joby Warrick in Washington contributed to this report.