To start with, here's an introduction to the ruling party, the Democratic Party (PD), its history, policies, support, and key figures.
The Democratic Party (PD) is relatively young, founded in late 2007 as a merger of various centre-left parties, including former Communists and former Christian Democrats. Chief among them were the Democrats of the Left and the Democracy is Freedom - The Daisy.
Like Italy's other major parties, the reason the PD was only formed quite recently is due to a massive corruption trial known as Mani Pulite (Clean Hands), which rocked Italian politics in the early 1990s by uncovering bribes and graft.
By the time it had run its course, 3,000 people had been arrested and half of the country's lawmakers had been indicted, bringing an end to Italy's First Republic, which had seen a series of centrist and centre-left coalitions, and paving the way for the creation of new parties.
Since 2013, Italy has been led by a PD government - and the party runs the majority of the country's regional councils too.
But the party has internal problems due to the range of views represented by its members. Earlier this year, a group of left-wing rebels left the party to form their own, criticizing the leadership style of ex-PM Matteo Renzi - who came to power as a result of an internal coup - and calling for "a left-wing renewal".
And there's friction between those who remain in the party, with Justice Minister Andrea Orlando heading up an anti-Renzi faction, and regular disagreement on policy.
The ideology of the Democratic Party can be hard to pin down due to the party's broad nature, but is inspired by social democracy. As the name suggests, it draws inspiration from the American Democratic Party: ex-PM Matteo Renzi was one of Barack Obama's closest international allies, and the party's first ever leader, Walter Veltroni, has been described as 'Italy's Obama'.
Matteo Renzi and Barack Obama. Photo: AFP
The PD is pro-Europe and has traditionally had a liberal attitude towards migration, though as Italy has come under increasing pressure from the ongoing wave of migration to Europe, its leaders have promoted stricter immigration policies.
The Democratic Party enjoys strong support nationwide, with control of 15 of the 20 Italian regions as well as the major cities of Milan, Bologna, Florence, and Bari. However, in 2016's regional elections it lost Rome and Turin to the Five Star Movement, something the party acknowledged was a "painful blow".
In the last two elections, it's had its best results in the centre and the north, particularly Tuscany, Emilia Romagna, Umbria, Le Marche, Liguria, and Lazio. Nationwide, the party is currently polling at about 30 percent of the vote, putting it neck-and-neck with the Five Star Movement.
The last major public vote before 2018's election took place in June, and while Renzi declared the results a victory for the PD, the party's performance was unremarkable while the centre-right emerged as the big winners.
The main risk for the PD is a potential lack of allies for a coalition, which will be needed if no single party gets an outright majority. After the June votes, Renzi said he would not rule out a coalition between the Democratic Party and Berlusconi's Forza Italia, suggesting he is concerned about the threat of a united right, though the parties are not natural allies.
Graph showing the average trend of opinion polling between February 2013 and May 2017. The Democratic Party is marked in red.
Former Prime Minister Matteo Renzi is the party secretary, having stood for re-election after he resigned following an embarrassing defeat in a referendum on constitutional reforms. Italy's youngest ever PM, Renzi was known as 'il Rottamotore' or 'The Scrapper' for his promises to do away with the old political guard, but his dogged pursuit of reform has left him with some enemies.
Current PM Paolo Gentiloni is less comfortable in the limelight, but is a trusted ally of Renzi leading a caretaker government. A one-time student radical, Gentiloni has had a long political career but didn't come to prominence until his appointment as foreign minister in 2014.
Culture Minister and former Party Secretary Dario Franceschini is also an award-winning author and lawyer, and considered one of the movers and shakers of the party. He leads the Christian leftist faction Democratic Area (AreaDem), of which Gentiloni is a member.
Dario Franceschini. Photo: AFP
Andrea Orlando was appointed justice minister by Renzi, and at the time Italian media reports said he was chosen as part of a deal made between Renzi and Berlusconi, because he presented little threat to the media magnate, whose legal troubles were hindering his political career. The 47-year-old, who does not have a university degree and previously served as environment minister, is still in the same position and also leads an anti-Renzi faction of the party.
Maria Elena Boschi is currently Secretary of the Council of Ministers. She started out in politics as Renzi's adviser when he was Mayor of Florence, and remains a strong ally of the former PM. Despite that, she was in charge of constitutional reforms under Renzi and led the 'Yes Committee' to promote his proposed reforms, which were rejected by the public and led to his downfall.