ISLAMABAD, Pakistan -- The assassination of opposition leader Benazir Bhutto deals a stunning blow to liberal political forces trying to combat rising Islamic extremism in Pakistan.

Gathering unrest by her supporters also risks tipping the volatile country into chaos, and puts additional pressure on President Pervez Musharraf as he struggles to keep order and stay in power.

It quashes hopes of Western governments that the charismatic, two-time former prime minister could team up with Musharraf and galvanize Pakistan's fight against Taliban and al-Qaida militants after Jan. 8 elections, which are now themselves in doubt.

"This assassination is the most serious setback for democracy in Pakistan," said Rasul Baksh Rais, a political scientist at Lahore's University of Management Sciences. "It shows extremists are powerful enough to disrupt the democratic process. Musharraf's major concern now will be to maintain law and order and make sure this does not turn into a major movement against him."

Bhutto died Thursday when an attacker shot her and then blew himself up as she left a political rally in Rawalpindi, a city near the capital where Pakistan's army has its headquarters. It was the second suicide attack against her since her tumultuous homecoming from an eight-year exile in October.

The other key opposition leader, Nawaz Sharif -- whose government was ousted in the 1999 coup that brought Musharraf to power -- quickly announced he was boycotting the parliamentary elections, which are meant to usher Pakistan toward civilian rule.

Talat Masood, a retired general and now a political analyst, expected Bhutto's party to follow suit -- a move that would rob the vote of legitimacy.

"Conditions in the country have reached a point where it is too dangerous for political parties to operate," Masood said.

He anticipated that Musharraf, who recently suspended the constitution for six weeks, could take drastic steps.

"It is possible they could declare an emergency again," he said.