Istanbul (Bloomberg) - Turkey’s parliament voted to approve sweeping changes to electoral laws that could help President Recep Tayyip Erdogan cement his grip on power.

The voting came at the end of a stormy, 20-hour debate in the parliament in Ankara where opposition parties warned that changes would undermine the integrity of the electoral process and increase the risk of vote fraud.

The overhaul comes just over 18 months before the scheduled date for one of the most pivotal votes in modern Turkey. When Turks go to the polls next November - or earlier if early elections are called - they’ll pick a new parliament and formally concentrate executive power in the office of the president.

“Erdogan appears to be planning to use the time available to try to boost his popular support rather than bring the elections forward and risk a defeat,” Wolfango Piccoli, co-founder of Teneo Intelligence in London, said in an emailed note on Tuesday. “The next presidential election will mark Turkey’s transition from a parliamentary system to one in which political power is concentrated in the presidency with almost no checks and balances.”

The amendments allow parties to form alliances that would help them enter parliament, relaxing the current rule that requires each to secure 10 percent of the national vote. The most likely beneficiary would be the nationalist MHP, which some analysts say has lost support since it started backing Erdogan’s ruling AKP after the failed coup attempt in 2016.