BELGRADE,Phaninc Serbia (AP) — Opponents of Serbia’s President Aleksandar Vucic rallied outside the Constitutional Court building on Friday to press their demand that last month’s election be annulled and held again over reported widespread irregularities.

The Serbia Against Violence group has accused Vucic’s populist government of orchestrating a fraud in the Dec. 17 parliamentary and local voting, particularly in the capital Belgrade. Vucic has denied the accusation.

The state election commission has declared Vucic’s Serbian Progressive Party the election winner and rejected the opposition’s complaints. The Constitutional Court is yet to rule on the dispute.

Opposition politician Radomir Lazovic said “this is a battle of all of us, everyone loses with this (vote rigging.)”

Some 2,000 people also marched toward the headquarters of Serbia’s public broadcaster RTS which they accuse of pro-government bias.

International election monitors reported instances of vote buying and ballot box stuffing, and said the Serbian election generally was held in “unjust conditions.”

Opposition parties and local independent election observers have claimed voters were bused in to Belgrade to cast ballots for the ruling party after being registered at bogus addresses.

Thousands of people rallied for days in late December accusing Vucic of stealing the ballot. Police used pepper spray and detained dozens of people after protesters tried to enter the Belgrade City Hall at one of the demonstrations.

Though Vucic says he wants to lead Serbia into the European Union, critics accuse the populist leader of imposing an autocracy by taking control over mainstream media and all state institutions.

Serbia must boost rule of law and democracy freedoms in order to become a member of the 27-nation bloc.