The first vote will take place on Wednesday afternoon, the second in the evening and the third on Thursday. If the government loses, it will be forced to resign. If the bill gets passed, it will then move to the upper house, or Senate.
The legislation, intended to harmonize the differing voting systems in the upper and lower house, has the backing of Italy's traditional parties but will penalize the insurgent Five Star Movement ahead of general elections, which are due before May 2018.
The reason being is that it would allow for coalitions to be formed ahead of elections, thus penalizing the party as it is has always pledged never to join an alliance. The Five Star Movement argues that the law is designed to prevent the party from ever winning an election.
The move to put the bill to a confidence vote was called by ruling Democratic Party (PD) whip Ettore Rosato, who proposed the law.
Rosato argued that it was “the fruit of a tough balance between the ruling majority and the opposition” and that putting it to “secret votes”, which is what killed off a previous electoral law in June, “would put the text as a whole into difficulty”.
But Luigi Di Maio, who was last month elected as the Five Star's candidate for prime minister, said the move violated democratic rules.
"This is an imperious step, which will prevent us to discuss any part of the bill," he said in a video message on Twitter.
Five Star Movement deputy Alessandro Di Battista protested outside parliament after the confidence vote was called, saying “democracy is in danger”.
The law would pave the way for two-thirds of parliamentary seats to be distributed on a proportional basis, with a third decided on a first-past-the-post system.
Recent polls show the PD, led by ex-prime minister Matteo Renzi, and the Five Star Movement, which recently nominated 31-year-old Luigi Di Maio as its candidate for prime minister, are neck and neck. But if the PD teams up with smaller centrist and left-wing parties ahead of elections they would likely eclipse the Five Star.
The new law could also favour Silvio Berlusconi's Forza Italia and Matteo Salvini's Northern League should the parties form an alliance.