After three centre-left prime ministers — Enrico Letta, Matteo Renzi, Paolo Gentiloni — over five years, Italians head again to the polls to elect a new national government on 4 March.

There are three main contenders but they won't be able to form a government on their own. This is all because of a new, mixed electoral system defined as “complicated” by the very party that introduced it.

The bookmakers’ favorite in this year's elections is the anti-establishment Five Star Movement party (M5S).

The civic movement, headed by Beppe Grillo, a former comedian, is set to be the largest single party and expected to win the most parliament and Senate seats. However, pollsters argue it won’t be enough to reach the 40% threshold necessary to have a governing majority in both chambers.

A new electoral law called Rosatellum, named after Ettore Rosato, the Democratic Party MP who pushed it forward, makes it hard for parties to win alone — putting a premium on coalitions and pitting candidates against each other at a local level.

This is a problem for the M5S, who refuse to strike deals with other political forces because their supporters will see any concessions as a moral compromise.

If they won’t bargain, it would be up to other parties to forge post-electoral compromises to get the numbers to secure a coalition government.

Main single parties standing

In addition to M5S, these are the other major political parties in this year’s election:

Democratic Party: The center-left force is being led by former Prime Minister Matteo Renzi. Paolo Gentiloni, the current head of the government, is running in his Rome constituency. A few months ago, the Democratic Party, known as PD, suffered a hemorrhage of MPs as smaller groups disagreed with labour and pension reforms. These MPs split to form a party that veered further left called Liberi e Uguali (Free and Equal). Most likely, it will be the second-most voted single party after M5S. January polls have it at around 25%, but it’s losing support on the left for being too centrist on social issues and employment.

Free and Equal (Liberi e Uguali): The party is spearheaded by former anti-mafia magistrate and Senate President Pietro Grasso, who is widely considered to put up an anti-Renzi fight. He's been criticised by many — including former Prime Minister Romano Prodi — for having destroyed the unity of the center-left, and leaving the country vulnerable to Berlusconi’s troops. Free and Equal’s main objective is to overhaul the current government's job reforms and replace it with a more leftist policy. It is polling at around 5-6%.

+Europa (More Europe): The liberal and pro-EU party is allied with the Democratic Party. Emma Bonino, a leading member of the Italian Radical Party and prominent activist for various civil rights battles, launched +Europa along with Christian-democratic economist Bruno Tabacci. The party’s electoral base is strong amongst well-educated youngsters, expats and left-wing supporters disillusioned by the internal struggle between PD and Liberi e Uguali. +Europa is polling just above 2-3%.

Forza Italia: Silvio Berlusconi is back. The controversial former prime minister boasts his name on the party symbol — but the media mogul is forbidden from running because of a 2013 tax fraud conviction. His clear and straightforward communication style is favoured among the elderly and voters in the south. Berlusconi has tried to rebrand himself as the man who can save Italy from populism. The party has yet to decide who will take the reins for Forza Italia should it form a government. Pollsters have Forza Italia at around 15%, making them the third-largest single force in Italian politics.

Northern League: Euroskeptic and right-wing, this controversial party is known in Italy simply as Lega, with its leader Matteo Salvini allied with Berlusconi’s Forza Italia. Over the past five years, Salvini has used anti-EU and anti-globalisation rhetoric as its supporters remain discontent with the economy and immigration. Salvini’s alliance with Berlusconi could prove difficult over the medium-term because of disagreements over key issues including Italy’s relationship with the EU. He boosted his party’s polling from 4.1% in 2013 to the current 13-14% with his persistent media presence and divisive social media posts.

Brothers of Italy (Fratelli d’Italia): This is the only main party led by a woman, Roman politician Giorgia Meloni. Described as “a southern equivalent of the Northern League with neofascist roots,” by the Guardian, the right-wing party is allied with both Forza Italia and Lega — alongside moderates Noi per l’Italia, UDC. Brothers of Italy could get up to 5% of the total votes.

What do they offer

Forming alliances might still not be enough

As Politico explains, under the Rosatellum electoral system, “37% of the parliament is elected locally, with the seat going to the candidate with the most votes in his or her constituency. The remaining 63 percent of seats are allocated proportionally via the use of short closed lists, with a small number selected by Italians living abroad”.

“This new system will force parties to compete in closely contested races constituency by constituency, investing heavily in dozens of micro-campaigns all over the country”. Tiny formations have to clear a 3% threshold to get into Parliament.

Italy has a long tradition of ground campaigning but nowadays parties’ structures are considerably weaker and their appeal to the general public has waned.

Each of the running parties appear unable to obtain a full, stable majority — and even coalitions may still struggle to win 40% of the total votes. Given that 30% to 40% of voters are still undecided, the so-called shy-factor in the polling process, which underestimates voting intentions for right-wing voters, and an abstention rate set to surge to above 30%, there are no sure bets in this election.

Lorenzo Pregliasco, co-founder of Quorum, a political strategy consultancy, and editor of YouTrend, a data analysis magazine, predicts three possible outcomes. All of the scenarios foresee a hung parliament.