ANKARA, Turkey — Turkey’s parliament on Monday began debating a set of changes to the country’s electoral laws which critics say are unconstitutional, designed to help President Recep Tayyip Erdogan consolidate power and may lead to election fraud.

A vote on the changes is expected sometime this week. Crucial presidential and parliamentary elections will be held next year, when Erdogan will need to secure 51 percent of the vote to remain at Turkey’s helm under a new presidential system that abolishes the prime minister’s office and greatly expands the president’s powers.

The elections are currently set for November 2019, but may be brought forward.

The changes would open the way for electoral alliances, allowing Erdogan’s ruling party to enter a formal alliance with the country’s nationalist party. That alliance would permit the smaller party to hold seats in parliament even if it doesn’t pass the 10-percent electoral threshold. In turn, Erdogan would secure the nationalists’ continued support at the presidential race.

The opposition has called the plans a “dirty alliance” that would give the smaller party an unfair advantage over other parties.

The main opposition party fears that other proposed amendments will give rise to fraudulent voting. They include allowing the government the right to appoint partisan government officials to oversee ballot stations, call in the security forces and to move ballot boxes.

The changes would also allow the electoral authority to count as valid ballot papers lacking an official stamp — a practice that had led to accusations of fraud during a referendum last year, which the opposition unsuccessfully challenged at a higher court.

Two opposition parties on Monday pushed unsuccessfully for the measures to be withdrawn saying they were unconstitutional.

The measures “shake the security of the ballots at the core,” opposition legislator Muharrem Erkek said. “Fair representation is being abolished.”

The ruling party says the amendments are required to ensure “electoral security” in Turkey’s mainly-Kurdish southeast region where it claims Kurdish rebels use threats or force to influence voters.

The ruling party and nationalists have sufficient majority for the amendments to comfortably clear parliament.