More than 7,740 candidates, nearly a third of whom are women, will compete for 329 parliament seats.

Here is a look at the general election and the key players.

- Turnout fears -

More than 21 million voters are eligible but there are fears turnout could drop below the 41 percent figure registered in 2021 -- the lowest so far.

An old electoral law will apply to the elections, with many seeing it as beneficial to larger parties.

Parliament restored the law in 2023, replacing a system installed after 2019 anti-government protests which favoured the emergence of independent candidates.

While around 70 independents won seats in the 2021 general election, only 75 independents are contesting seats in Tuesday's vote.

- Shiite majority -

Iraq's Shiite Muslim majority has had the upper hand in Iraqi politics since the overthrow of Saddam's Sunni Arab-dominated rule.

Following the 2021 polls, powerful Shiite parties came together under the umbrella of the Coordination Framework to form Iraq's largest parliamentary bloc.

The Framework became a ruling alliance of factions with varying links to Iran, which has brought current PM Mohammed Shia al-Sudani to power.

These groups are running separately in the election, but they will likely reunite afterwards to name a new PM and form a government.

The main Shiite lists include:

- The Reconstruction and Development Coalition of PM Sudani, who is hoping for a second term and is expected to score a big win.

- The State of Law Coalition led by former prime minister Nuri al-Maliki, who despite his controversial past still holds sway in Iraq's politics.

- The National State Forces Alliance of senior politician and cleric Ammar al-Hakim, who leads the moderate Shiite camp.

- The Al-Sadiqun list of faction leader Qais al-Khazali, who the US designates a terrorist but has emerged in recent years as an influential politician.

- The Badr organisation led by Hadi al-Ameri. It is one of the biggest pro-Iran factions within the Hashed al-Shaabi, a network of former paramilitary units that have been integrated into the regular security forces.

- The Huquq list, which is close to Kataeb Hezbollah, a pro-Iran armed faction designated as a "terrorist" group by the US.

Observers predict the main Shiite competition to be between Maliki and Sudani, who launched his political career in 2010 in Maliki's government.

- Sunni divide -

Sunnis are running separately, with the main list belonging to influential former parliament speaker Mohammed al-Halbussi, who leads the Taqadom party (Progress). He is expected to score a big win.

His main competitor is the Al-Siyada Alliance (Sovereignty) of controversial Sunni politician and US-sanctioned businessman Khamis al-Khanjar, and parliament speaker Mahmoud al-Mashhadani.

A third list, Al-Azm alliance (Determination), is led by lawmaker and businessman Muthanna al-Samarrai.

- Kurdish rivalry -

Autonomous Kurdistan in northern Iraq has long been dominated by two parties: the Kurdistan Democratic Party (KDP) and the Patriotic Union of Kurdistan (PUK).

Opposition party New Generation has also emerged in recent years. Its leader Shaswar Abdulwahid was sentenced in September to five months in prison over an old defamation case.