Tunisia was always the clearest contest of the Arab Spring, with rather evenly balanced secular and Islamist forces fighting for the right to shape the country. Now it's fast becoming a battleground. 

The assassination this week of opposition firebrand Chukri Beleid broke the patience of the country's secular labor unions, and more violence is certain to follow.

Beleid was an outspoken figure on the political left, in a country where left-leaning labor unions with mass memberships were the prime organizing force of the revolution that toppled President Zine El Abidine Ben Ali in 2011. Beleid was killed the morning after he went on TV accusing a faction inside the Islamist Ennahda party, which heads a coalition government, of being behind attacks on the opposition.

In Gafsa, the mining town where anti-Ben Ali riots in 2008 foreshadowed the revolution, union protests quickly turned violent. Rioters called for the fall of the country's Islamist-led government and threw gas bombs at the police.

The main General Union of Tunisian Workers, better known as the UGTT, has called a general strike for Feb. 8, the first since 1978. That strike is still remembered for the arrests, violence and 42 deaths that followed. Worries of a repetition caused the union to call off a strike it had planned in December, but this time it will go ahead.

Say what you like about Tunisia's Islamist Prime Minister Hamadi Jbeli, but he made the right call in offering to dissolve the government and form a technocratic one until early elections, in response to Beleid's murder. When his own Ennahda party disowned the move, it became clear that Jbeli also made a politically brave call.

Although Beleid accused Ennahda of organizing salafist attacks, and his family and supporters accuse Ennahda of killing him, nothing is clear. In Tunisia, unlike Egypt, salafists have shallow popular support, so even salafist political leaders insist that the gangs trashing art galleries, union offices, Sufi shrines and other targets are invented as part of a destabilization campaign. By whom is not clear.

Beleid was right, however, that Ennahda is a divided party in which Jbeli represents the moderate wing. Ennahda's better known leader, Rachid Ghannouchi, is cut from a different cloth. By offering to dissolve the government, Jbeli was trying to rescue the country's democratic experiment -- he blamed the assassination on opponents of the revolution and democracy. 

Relinquishing power now would allow the constitutional assembly -- which doubles as a parliament -- to focus on its day job and complete a new constitution, without which Tunisia can make little real progress, economically or politically. Early elections would also help to clear the air.

Ghannouchi, however, reacted by calling a party meeting, after which Ennahda rejected Jbeli's call for an apolitical cabinet and insisted that the current governing coalition stay in place. If any one person must shoulder the blame for the mess Tunisia is now in, it must be Ghannouchi, who has used the moral authority he enjoyed as a dissident leader under Ben Ali to fight a zero-sum struggle to determine Tunisia's identity as an Islamist country -- precisely because he knows it's not one. Oxford professor Mohamed-Salah Omri has given a good account of how Ghannochi has helped make Tunisia a battleground for Islamist identity politics.

A video leaked in October that shows Ghannouchi talking to salafists seemed to confirm the worst fears of his opponents that Ennahda was using salafists to reach its Islamist goals, even while insisting it is a moderate party committed to democracy. 

"Secularists still control the economy, the media and the administration," Ghannouchi told the salafists, urging them to build Koranic schools, draft preachers and set up TV stations to turn the population to Islam -- which is to say Islamism, given that even secularist Tunisians tend to be observant. Ghannounchi's supporters said the meeting took place months before in February, and the clip was out of context.

None of this means that Ennahda or Ghannochi ordered the assassination or salafist violence. But Ghannouchi and his party have overreached and have been unwilling to crack down on Islamist foot soldiers. Jbeli clearly understands this, and that a new start with fresh elections is needed. The next Tunisian polls will require saturation level international monitoring to ensure they are, and are perceived by Tunisians to be, free and fair. That is even more true if Ghannouchi gets his way and Ennahda's government remains in power until voting day.

In the meantime, just hope that Tunisia doesn't deteriorate into another revolution -- this time without the removal of a hated dictator to provide a clean ending. 

(Marc Champion is a member of Bloomberg View's editorial board. Follow him on Twitter.)