Tens of thousands of supporters of Armenia's protest leader, Nikol Pashinyan, have responded to his call for civil disobedience, blocking key roads and government buildings.
He has led weeks of anti-government protests that forced Serzh Sargsyan to resign after 10 years in power.
Mr Pashinyan called for a general strike after ruling party MPs refused to back him as interim prime minister.
Protests broke out across the capital Yerevan and other main cities.
Cars and lorries blocked intersections in the capital, while demonstrators stopped traffic on the route to the main airport. Tourists had to abandon vehicles and carry their luggage. Metro stations in Yerevan were closed as part of the campaign of disobedience.
Teachers and school students were among those taking part in the protests in the landlocked former Soviet state of 2.9 million people, a close ally of Russia. The southern Caucasus country shares borders with Turkey, Georgia, Iran and Azerbaijan.
Entrances to several ministry buildings were blockaded and rail services were also disrupted. Trains were not running between Yerevan and the second city, Gyumri, and checkpoints near the Georgian border were affected.
There was further disruption in Gyumri itself and in the third city Vanadzor, where a large crowd of protesters blockaded the mayor's office and other civic buildings. Three thousand workers from a local sewing factory walked out and cut off some of Vanadzor's biggest roads, reports said.
The demonstrators took to the streets after Mr Pashinyan addressed crowds on Tuesday night in Yerevan's Republic Square, close to parliament, saying that police should also join the protests.
He told the BBC on Wednesday that protesters were fighting for their own rights and dignity. "I want to be clear, it isn't a fight for Nikol Pashinyan becoming prime minister, it's a fight for human rights, for democracy, for rule of law and that is why our people aren't tired and won't be tired."
During the day he posted a message on social media urging protesters to halt disruption at the airport, while other opposition politicians appealed to people not to impede emergency services. Police tried to move protesters off the roads but there was no sign of violence.
Mr Pashinyan fell eight votes short of the 53 he needed to secure a majority in the 105-seat chamber on Tuesday, when he failed to persuade the ruling Republican party to back him.
He warned them during a marathon nine-hour question-and-answer session of what would happen if they rejected his candidacy. "Your behaviour, treating the tolerance of the people as a weakness, could become the cause of a tsunami."
Parliament is expected to try again to elect a prime minister on 8 May.
Republican MPs had reportedly given assurances they would not block Mr Pashinyan's bid for office and did not put up their own candidate in a bid to ease tensions. But some MPs accused him of bringing chaos to the streets and questioned whether he was up to the job.
"Mr Pashinyan, I don't see you at the post of prime minister, I don't see you at the post of commander-in-chief," said Eduard Sharmazanov, deputy speaker of parliament and Republican spokesman.
Mr Pashinyan's supporters shouted "shame" when the result of the parliamentary vote was shown on two huge screens in Republic Square.
The opposition leader, accompanied by his wife, arrived in the square soon after, with the crowd chanting "Nikol, Nikol".
How did we get here?
Mr Sargsyan left the presidency last month after 10 years in power and was then elected prime minister by a parliament controlled by his Republican party. Under a 2015 referendum marred by irregularities, Armenia has shifted powers from the president to parliament.
Mr Sargsyan's move was seen by critics as a way of clinging to office and demonstrators poured onto the streets of Yerevan in protest.
Mr Pashinyan then met his rival for talks, which broke down within minutes when he called for the prime minister's resignation and Mr Sargsyan accused protesters of blackmail.
Mr Pashinyan and about 200 protesters were then arrested.
However, Mr Pashinyan was soon released and the prime minister resigned, admitting he had "got it wrong".
Mr Pashinyan has said he will rid Armenia of corruption, poverty and nepotism and has promised snap elections.
Who is Nikol Pashinyan?
The son of a sports teacher, Mr Pashinyan came to prominence in 1995 when he began writing about government corruption. He founded a newspaper three years later and went on to take the role of editor at a best-selling daily, which criticised the government of President Robert Kocharyan and then of President Sargsyan.
When Mr Sargsyan was elected president in 2008, Mr Pashinyan was among the leaders of protests that turned violent and left 10 people dead. At that point he went into hiding, surrendering to authorities the following year.
Jailed the following year on charges of murder and organising mass unrest, he was eventually released under an amnesty in 2011.
In 2012, he was first elected to Armenia's parliament. He argues that only he can steer Armenia to free and fair elections.
