Pervez Musharraf promised to lift Pakistan's state of emergency by Dec. 16 and restore its constitution before January elections, a key demand of his domestic opponents and foreign backers.

"I am determined to lift the emergency by Dec. 16," Musharraf said in a televised address to the nation. "The elections, God willing, will be held free and transparent under the constitution."

Hours after the former military strongman was sworn in as a purely civilian president, Musharraf appealed to two former prime ministers recently returned from exile to drop their threats to boycott the Jan. 8 parliamentary elections.

"Benazir Bhutto and Nawaz Sharif have come back, and a level playing field has been given to (their parties). Now it is the responsibility of these and other parties to prepare for the elections, and participate fully," he said.

Witnesses say violent clashes broke out between lawyers protesting against President Pervez Musharraf and police in the eastern city of Lahore immediately following the ceremony.

"This is a milestone in the transition of Pakistan to the complete essence of democracy," Musharraf told an audience of government officials, foreign diplomats and military generals. "Elections will be held in January come whatever may."

On Wednesday, a tearful Musharraf ended a four-decade military career as part of his long-delayed pledge not to hold both jobs.

The United States, keen to promote democracy while keeping Pakistan focused on fighting Islamic extremism, praised Musharraf's relaxation of his grip on power as a "good step" forward.

But it gave him no slack on the other key demand that he end a state of emergency that has enraged political rivals, strained his close ties with the West and cast doubt on the ability of opposition parties to campaign for the parliamentary elections.

"We welcome Musharraf's decision to shed the uniform," Bhutto said Wednesday. "Now the Pakistani army has got a full-fledged chief and they can better perform their duties."

But she said her party would "not take any decision in haste" on whether it could accept Musharraf as head of state.

Sharif again rejected Musharraf's presidency, saying his presidential oath would have "no legitimacy."

Musharraf first promised to quit the army at the end of 2004 but broke his word, saying the country needed his strong leadership. He told The Associated Press in an interview this month that his presence was vital to ensure stability.

Outgoing lawmakers re-elected Musharraf to the new five-year term in October. But the Supreme Court held up his confirmation following complaints that a military officer could not run for elected office under the constitution.

Musharraf reacted by proclaiming a state of emergency on Nov. 3, sacking the chief justice and other independent judges and replacing them with his appointees. The reconstituted top court then duly approved his election.

Officials have indicated emergency rule might be lifted soon, but have not set a firm date.

President Bush said he appreciated that Musharraf kept his word by relinquishing his military post, calling it "strong first step" toward enhancing democracy in Pakistan.

"It is something that a lot of people doubted would ever happen," Bush said in an interview with CNN's "The Situation Room."

But Bush added that "in order to get Pakistan back on the road to democracy, he's got to suspend the emergency law before elections."

After more than 40 years in the army, Musharraf now will have to jostle for power with Bhutto and Sharif. Both have registered as candidates in the elections, and say they will boycott the ballot only if the entire opposition agrees to — something considered highly unlikely.

Sharif, who returned from exile on Sunday, has taken a particularly hard line against Musharraf, who ousted him in the 1999 coup.

A conservative comfortable with Islamic parties, Sharif has been reaching out to the many voters who oppose Pakistan's front-line role against the Taliban and al-Qaida, styling Musharraf as an American stooge.

Emergency rule has also strained Musharraf's relations with Bhutto, who shares his secularist, pro-Western views and has left the door ajar for cooperation.

Musharraf has relaxed some aspects of the crackdown. Thousands of opponents have been released and all but one news channel is back on the air. However, he has refused to reverse his purge of the judiciary, an act that pitted him against Pakistan's well-organized legal fraternity.

On Wednesday, about 400 lawyers staged a protest about 2 miles from army headquarters, shouting "We want freedom!" and "Hang Musharraf!"

"He should be thrown out," said Sardar Asmatullah, a lawyers association leader. "He has been a dictator for the last eight years and he has delivered nothing good for this country."