Interior Minister Ali al-Areed, who denied any involvement by his party, vowed to track down the killers and joined the chorus of moral indignation, calling Belaid's assassination "an attack on all Tunisians."

At the same time, he asked that protests remain peaceful. "We do not want the country to fall into chaos," he said on Tunisian state TV.

Lise Storm, a senior lecturer in Middle East Politics at the University of Exeter in England, warned against overplaying the significance of Belaid's death in the long term and said the current protests are in part driven by more general discontent.

While Belaid was a well-known figure, his party is small and has no real political platform other than opposition to Ennahda, she said.

Although it remains unclear who might have been behind his murder, it is highly unlikely that Ennahda played a role, as some have alleged, she said. The party is moderately Islamist and is made up of seasoned politicians who have waited a long time to be able to govern, she said.

Storm suggested that any move to dissolve the current elected government would be counterproductive, since a unity government would find it difficult to reach consensus on reforms. Tunisia has made great progress toward democracy in the past two years, she pointed out, with presidential elections expected after the new constitution is approved, likely later this year.

Popular discontent is focused on the issue of jobs and speedier reform of the police and other institutions, particularly in places such as Sidi Bouzid, which were at the center of past political protests, she added.

Women's Minister Sihem Badi told CNN that it was important that Tunisians remain united at this difficult time.

People are worried that the upheaval may lead to a return to the situation as it was before the Arab Spring revolution, said Badi, a member of the Congress for the Republic party.

To prevent that from happening, it is vital that Tunisia remains committed to the process begun two years ago, she said, with the country's political parties, media and civil society coming together to safeguard the freedoms and democratic progress won by the people.

"We must protect our revolution," she said. "We need time, we need patience, we need the agreement of many partners -- we can't work alone."

Badi said the violent protests that broke out Wednesday were a natural response to the shocking death of Belaid. But, she said, such clashes are unusual in Tunisia and she does not expect them to continue.

"We have a very difficult period now, but it's important to prepare good conditions for future elections," she said, including agreement on a new constitution.

Belaid was shot by an unknown gunman as he left his home in a quiet Tunis suburb for work Wednesday morning, according to a witness.

The attack was "a clear message to Tunisians ... shut up, or we kill you," Abdelmajid Belaid said. He said his brother had been "receiving threats of murder for a long time," including a text message Tuesday.

And Chokri Belaid's widow, Basma, told Tunisian state TV: "We are damned. The political struggle is damned in Tunisia. Chokri Belaid sacrificed his soul."