Story highlights An online video has come to represent a stark choice about the future of the country

One video is speaks about what would happen if Islamist groups take power

In response a video was posted by Tunisian Islamists

There are about 100 parties vying for votes

The people of Tunisia, who lit the fuse for protests that have ignited the Arab world, cast their votes for a constituent assembly this weekend. Ahead of this critical vote, one online video has come to represent a stark choice about the future of the country.

The video is part of a guerrilla war between secular and Islamist groups waged through social media. It says much about a climate of growing suspicion and mistrust in the first Arab country to expel the old order -- a climate that has already led to bouts of violence.

Against a background of melancholic music, the 45-second video entitled "The Day After" shows a woman sitting on a sofa with her two daughters. She speaks as if Islamist groups have taken power and says her husband "told me they could be trusted. I believed and I followed."

Then she adds: "After a few months, they changed the law. He married two other women. ... I forfeited my family's happiness. ...I betrayed my daughters' futures."

Tunisian Islamists have responded by posting their own version of the video -- with a very different twist to the woman's words.

"I was told, 'Be careful, pick any party except them. They're backward,'" says the dubbed version. The woman speaks of Tunisia as a police state. "They even came to my office to tell me, 'You either take off this rag off your head or quit your job'" -- a reference to whether women would be allowed to wear the veil in public in a secular Tunisia. Under the old regime, women wearing headscarves often found it difficult to find employment.

The dubbed video ends: "Together against the anti-Islam campaign. Tunisians: your vote is your trust."

The two versions of this one video are the starkest illustration of what has become a dominant theme in the campaign for a constituent assembly that will devise a new constitution: the role of Islam. It is a debate that is being played out across the Arab world as it wrestles with alternatives to authoritarian rule. In Tunisia, the euphoria of driving President Zine el Abidine Ben Ali from power ten months ago has long since dissipated.

The original video was one of five created and posted on Facebook and YouTube by business supporters of a secular Tunisia.

None mentions a political party by name. One of the videos shows a young waiter in an empty restaurant. "My boss is ruined. The restaurant is failing," he says. The message: Islamists would introduce strict laws about drinking and socializing, scaring off Tunisia's all-important tourism trade.

In recent weeks, the debate in Tunisia has taken to the streets with violent consequences. Islamist groups protested in Tunis earlier this month after a local television network broadcast an animated film called "Persepolis," which at one point depicts God, an act of blasphemy to many Muslims. The protest turned violent as police intervened with tear gas.

A subsequent march by Islamist Salafist groups on the prime minister's office last week was also dispersed. In addition, there was also an attack on the home of the TV station's owner.

The most prominent Islamist party, Ennahada, condemned the violence but would not disown the protests, describing the film as provocative.

The stakes in this election are huge for Tunisia but will also resonate across the Muslim world. A first-place showing for Ennahada -- even if an outright victory seems unlikely -- would encourage other Islamist parties across the region.

But it would also pose questions about Islamist rule and democracy. Would Ennahada impose a conservative social code on what is one of the most secular and industrialized Arab countries? Or would it follow the model of Turkey's ruling Justice and Development Party showing that Islam and democracy are compatible?

Ennahada's leadership has insisted it offers the latter. Leader Rachid Gannouchi, who returned to Tunisia in January after two decades in exile, has said he is "no Ayatollah Khomenei" and has promised his party would protect women's rights and work with other political parties. The party's rallies have attracted many women.

Gannouchi has suggested that Tunisia needs a coalition government for the next several years to deal with the nation's chronic problems, especially unemployment, which is estimated to be running at some 15%.

One recent survey suggests that while a third of Tunisians are focused on Islamic values, nearly 60% say unemployment -- the issue that kick-started the unrest at the end of 2010 -- is their priority.

There are about 100 parties vying for votes, but it is difficult to assess their strength. Authorities have banned campaign advertising and polling -- and even the size and placement of election posters has been tightly controlled.

Since the campaign officially began, the newly-liberated Tunisian press has been banned from interviewing politicians. Instead, candidates are allowed a three-minute television appearance.

The interim government says the measures are intended to ensure a level playing field where money can't buy media prominence. Secular parties have complained they make it difficult to reach citizens beyond their urban, middle-class constituency. Ennahada has an organizational advantage because even though it was driven underground by Ben Ali, it kept a grass-roots presence in much of the country, often working through mosques. More voters say they have been contacted by Ennahada than by any other party.

Private polling obtained by CNN suggests that Ennahada may win a quarter of the vote, and the Progressive Democrats about 10%. Another secular party, Ettakatol, may win about the same amount. But 50% of Tunisians say they are undecided and the rest of the vote could be split by dozens of groups. And there are nearly 600 independent candidates.

Writing a new constitution for the country that won international acclaim for its Jasmine Revolution will be more like wading through brambles.