Several thousand protesters took to the streets of the Armenian capital after talks between the opposition and the acting prime minister were called off.
Pressure on the government increased in the evening when the dominant party’s small coalition partner, Dashnaktsutyun, announced it was withdrawing.
The move leaves the governing Republican party with a majority of 58 seats in the 105-member parliament.
Protest leader Nikol Pashinian had been expected to sit down with the acting prime minister to discuss political transition after prime minister Serzh Sargsyan abruptly stepped down on Monday amid massive anti-government protests.
Acting prime minister Karen Karapetian is an ally of Mr Sargsyan, who ruled Armenia for 10 years.
The opposition insists that he step down soon to make way for a new premier appointed by a new parliament.
The talks on Wednesday were supposed to discuss that transition.
Mr Karapetian said in a statement that the talks with Mr Pashinian were cancelled after the opposition made unspecified “unilateral demands”.
Mr Pashinian called on his supporters to take to the streets in protest.
About 5,000 people marched in the centre of the capital, Yerevan, blocking traffic and chanting “Join us!”
Protesters danced on the streets and waved the Armenian flag.
Outside of Yerevan, demonstrators blocked several major roads including the road to the airport.
“Authorities won’t step down, they are just dragging their feet,” said 24-year-old protester Garik Migranyan.
“But we will make them do that. We are the power.”
Armen Tankyan, who was at the main square with his 11-year-old son, said people have lost trust in the authorities, while “the opposition promises change for the better”.
Armenia’s sports minister on Wednesday sided with the protesters, telling the demonstrators on the Republic Square that he is resigning.
“We will not allow authorities to steal our victory,” Mr Pashinian told supporters.
“There will be more of us here with every day until we take power.”
Mr Pashinian said he and his allies would boycott the snap parliamentary election if a member of the ruling Republican Party remains prime minister.
The opposition insisted that “a people’s candidate” should replace Mr Karapetian.
Mr Pashinian has indicated his willingness to become premier if people support him.
Mr Pashinian called for a rally on Yerevan’s main square on Wednesday evening, when a new prime minister will be nominated.
The nominee would need to get parliament’s approval and is expected to oversee the upcoming snap election.
He said later on Wednesday that he met with the ambassadors of several European Union nations and was preparing meetings with the US and Russian envoys.
Mr Sargsyan said in a statement he is concerned about the tensions in the country and would launch talks with pro-government and ruling parties in search of compromise.
Analysts warned of escalation as the protesters made it clear that they would not settle for the mere ousting of Mr Sargsyan, instead, they seek a genuine change of the whole political leadership.
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