Italians casting their votes Sunday are heading into an unpredictable future, with polls pointing to a high likelihood of a hung parliament.

The ruling center-left Democratic Party (PD) has seen a drop in support amid political infighting, while the group with the best chance of success — a center-right coalition under three-time former Prime Minister Silvio Berlusconi — doesn't look to have a certain majority.

Not even the single most popular party, the anti-establishment 5Star Movement, looks close to clinching a win.

POLITICO's live blog has the latest news, reaction and analysis. And here is a POLITICO guide to help you navigate the confusion:

Who are the main parties and politicians?

Berlusconi is leading his Forza Italia party into the vote, though he is barred from holding public office. On Thursday, Berlusconi officially named European Parliament President Antonio Tajani as his pick for prime minister. Tajani, who has denied this for months, tweeted that he had informed Berlusconi of his “willingness to serve Italy.”

The campaign has been a bit of circus in some ways.

The Northern League, running in coalition with Berlusconi, is a traditionally Euroskeptic party that, under Matteo Salvini's leadership, has softened its attacks on Brussels and dropped its calls for a referendum on the euro. However its “Italy first” message could put it at loggerheads with Brussels.

By far the most popular single party, according to polls throughout the campaign, is the anti-establishment 5Star Movement under Luigi Di Maio. According to the last published polls in mid-February (it is illegal to release fresh polls in the last two weeks before the election), it was leading with between 27 and 29 percent. Di Maio has worked hard to show that, after years in the opposition, the 5Stars are ready to govern.

Former Prime Minister Matteo Renzi’s Democratic Party is set to take a pummelling. Polls taken just before the ban went into effect on February 19 put the PD's support at under 23 percent, largely due to discontent with Italy's slow economic recovery and high unemployment.

How's the campaign been?

A bit of circus in some ways.

Parties have decided that, because it looks to be a close election (especially due to a new electoral system), and because the new system is largely proportional, they need to compete fiercely to make themselves stand out to voters, even against their own coalition partners. Politicians have been promising everything from reopening and taxing brothels, to providing free visits to the vet, as well as tax cuts and higher pensions. Collectively, their political pledges would cost about €1 trillion, according to Italian media.

"So many false pledges have increased the anger of voters,” said pollster Roberto Weber. However, they may not be fooling voters: In a survey published in the first week of February by the daily Il Fatto, 72 percent of Italians polled said they didn't trust any such promises.

What happens on election day?

Italians will vote between between 7 a.m. and 11 p.m. for both chambers of parliament: 630 members of the Chamber of Deputies and the 315 elected members of the Senate. Both houses are elected every five years, unless parliament is dissolved early. But Italy’s voting-age are quite particular: Citizens aged 18 and older can vote for the Chamber of Deputies, but they must be at least 25 to vote for the Senate.

The difference in voting-age rules often delivers different majorities in each house, which can make things tricky when both houses have to give a vote of confidence on the new government.

The Senate also includes life members appointed by the president, as well as former Italian presidents who serve as ex-officio life senators.

The majority threshold is 316 seats in the lower chamber and 158 for the Senate.

How does voting work?

Italian lawmakers passed a controversial electoral law last year that will now be implemented for the first time.

“At the moment there are five likely governments” — Political analyst Luca Ricolfi

Under the new system, about 37 percent of lawmakers in both houses are elected locally, with the seat going to the candidate with the most votes in his or her constituency. The remaining seats are allocated proportionally via the use of short closed lists, and a small number are selected by Italians living abroad.

But the system also has provisions that give advantages to pre-election coalitions, for example by automatically sending a vote for a candidate in the first-past-the-post constituency to the supporting coalition and vice versa. The 5Stars, who have long refused to join any coalition (though that could change), opposed the law, arguing that it was designed by the main parties to prevent the 5Stars from gaining power.

Electoral experts have warned that for all these reasons, the system may not be able to produce a clear-cut winner.

What’s the best way to follow the action?

POLITICO will be running a live blog from midday Sunday through Monday. Given that polling stations close so late, broadcasters like La7 and Rai don’t kick off their election specials until 10:30 p.m. or 10:45 p.m. These shows are scheduled to run into the early hours of Monday as results come in.

When will we know the results?

Though exit polls will be released shortly after voting centers close at 11 p.m., don't expect concrete results until Monday morning, especially because the outcome could be close or inconclusive. Even when the final tallies are in, it still may not be clear what they mean in terms of who could make up a new government.

"At the moment there are five likely governments” according to political analyst Luca Ricolfi.

What are the possible outcomes?

The five scenarios are: a center-right victory; a coalition of Renzi's PD, Berlusconi's Forza Italia and centrist parties; a coalition of the PD, the 5Stars and the far left; the 5Stars and the Northern League; and the 5Stars together with the far left.

The last two options are deemed the least likely, while an alliance between the 5Stars and the PD also looks highly improbable. “I rule it out,” said a senior official in the current PD government.

Berlusconi's coalition has the best chance of winning.

One strong likelihood is a hung parliament where no one gets the key threshold of 40 percent of votes to form a governing majority.

This could lead to a larghe intese — a grand coalition — made up of a great number of parties including Berlusconi's center right and Renzi's center left. However, the main parties ruled this out during the campaign.

Berlusconi's coalition has the best chance of winning, though it was only poll at between 35 and 38 percent back in February.

It's also important to note that pre-election coalitions can easily change after the vote and that there is no electoral bonus that would award automatic seats to the first-placed list or coalition.

Who teams up with who has been the subject of constant rumor and speculation in the run-up to the vote. One report said the 5Stars were mulling a pact with the Northern League, others had them considering a pact with the center left, and yet another said Berlusconi was eyeing a small pro-EU party led by former EU commissioner Emma Bonino.

What if there is a clear winner?

After consulting with the political parties, President Sergio Mattarella will pick whoever looks most able to form a government, then both houses must hold a vote of confidence to confirm the new government.

What if there's a hung parliament?

In theory, the country could hold a new election soon, but that's very unlikely. One reason is that Italians elected to parliament will be reluctant to forego pay which, according to Italian media estimates, can total more than €13,000 a month, far exceeding the pay of their EU colleagues. That compares to the average Italian family's net earnings of about €30,000, according to official data from Istat.

There are other reasons another election is unlikely. Peter Ceretti, Italy analyst at the Economist Intelligence Unit, said "there is no time limit on forming a government in Italy, as there is in Spain or Greece, where rerun elections have been held in recent years.” Negotiations are “likely to continue until a broad coalition is formed, probably including a number of centrist parties and possibly some members of parliament who break ranks with opposition formations to prevent a new election,” he said.