Italians demonstrate on Nov. 27 in Rome against a referendum on proposals designed to curb gridlock in Parliament. Publication of polls is prohibited in Italy during the last two weeks before a vote, although many find ways to outflank the ban online. (Massimo Percossi/European Pressphoto Agency)

MILAN — On Sunday, Italians will head to the polls to vote in a referendum that could change the political course of their country. But they won't be compulsively checking polls while they wait: In Italy, it's illegal to publish polls during the final two weeks before a vote.

The referendum is about changing Italy's constitution to smooth the work of Parliament, which is notorious for its slowness, by eliminating its “perfect bicameralism,” the system that requires any step in the drafting of a law to be approved by both the lower house and the Senate.

Critics argue that the proposed amendment would take too much power from the Senate. But the real key issue is the prospect of the resignation of the prime minister, the liberal Matteo Renzi, who has vowed to quit if the referendum fails. That development could galvanize the country's populist forces and “turn Italy into the 'third domino' in a toppling international order, after Brexit and the election of Donald Trump,” as the Economist put it last week.

In the last official polls, published on Nov. 23, the “No” vote had a slight advantage. But that is hardly predictive of the outcome, according to observers. “The problem is that public opinion tends to change a lot in the final weeks before the vote, so the ban has a significant impact,” said Ilvo Diamanti, a sociologist and pollster.

Italy has one of the world's strictest laws regulating political campaigns. Introduced in 2000, it was originally aimed at containing Silvio Berlusconi, the media mogul turned politician, as legislators feared he might use his three TV channels to skew public opinion, for instance by broadcasting misleading surveys.

“Polls aren't simply about registering public opinion, but also helping to shape it,” Diamanti said. “It's a phenomenon known as the 'spiral of silence theory': Some people tend to conform, so when an opinion is declared 'dominant,' it can become more popular, in a self-fulfilling prophecy.”

According to a 2012 University of Hong Kong study, 38 countries prohibit the publication of polls in the last days of a campaign, but only a handful (Argentina, Greece, Honduras, Ukraine and Italy) do so for as long as two weeks.

These bans “create more problems than they solve,” said Lorenzo Pregliasco, co-founder of Quorum, an Italian polling agency. Since the law forbids only the publication of polls, not the collection of data, political parties still commission surveys up to the day of the vote, even though their results cannot be made public. “This only creates a knowledge gap between the leaders and the general public,” Pregliasco said.

But times are changing. In recent years, those who get their information online — which includes most young people — find it quite easy to get around the law. Blogs bypass the gag by pretending to publish forecasts about imaginary events, when they are actually releasing leaked data from last-minute polls.

The conservative website the Right Nation, for example, is keeping its readers updated about forecasts concerning a fictional horse race to be held on Dec. 4. (Only two horses will run, one that happens to “always say Yes” and the other “a notorious naysayer.”) YouTrend, a blog sponsored by Quorum, features a bizarre poll about Catholic cardinals and their preference in saints: Purportedly, 55 percent of them are devoted to Saint Norbert while 45 percent favor Saint Simplicius. Readers can easily guess that “Norbert” stands for a No in the referendum and “Simplicius” for a Yes (Sì in Italian), while “cardinals” is a code-word for Italians.

Pregliasco declined to confirm that interpretation. But the fact that the blog's homepage features a picture of Jude Law in the TV series “The Young Pope,” rather than a real cardinal, leaves few in doubt about the double meaning implied.