Supporters of Armenia's protest leader Nikol Pashinyan rallied in the capital on Sunday, hoping that a massive show of force two days ahead of a key election will help propel the opposition leader to power.
Pashinyan, who needs a handful of votes to become the country's next prime minister, saw his chances boosted Sunday when a senior lawmaker said the ruling Republican Party would not stand in the way of his candidacy.
In the streets of Yerevan, flag-draped demonstrators blocked intersections, sang songs, played music and chanted slogans accusing the ruling party of clinging to power against the people's will.
Serzh Sarkisian, who became prime minister on April 17 after serving a decade as president in what was seen by opponents as a power grab, resigned on Monday after 10 days of protests.
Protester Vigen Arabyan said the Republicans had no choice but to throw in the towel and back the hugely popular Pashinyan, 42.
"We simply cannot continue on this path," the 51-year-old engineer told AFP. "The country is going towards complete destruction if we keep going this way."
Arut Khachatryan, a 17-year-old high school student, added: "We are witnessing a decisive moment" at the culmination of two weeks of severe political crisis in the country of 2.9 million.
Pashinyan, who heads the small Civil Contract party, is the only candidate in the running for the premiership so far and insists that only he can rid Armenia of corruption, poverty and nepotism.
On Friday and Saturday, Pashinyan received a hero's welcome in a number of towns and villages outside the capital as he drove around the landlocked ex-Soviet country with his supporters in a convoy.
He needs the backing of at least six lawmakers from the ruling Republican Party, which has 58 seats in parliament, to clinch victory on Tuesday.
The party has said it would announce its position on Monday, but Pashinyan said he had already received an assurance from the head of its parliamentary group, Vahram Baghdasaryan, that it would not sabotage his bid.
"Lawmakers of the ruling party are inclined not to stand in the way of my candidacy," Pashinyan said.
On Saturday, after days of frantic negotiations, two major parties said they would back Pashinyan, but he was still six votes short of the 53 he needs from the 105-seat legislature.
The Prosperous Armenia Party, which holds 31 seats, threw its weight behind Pashinyan on Saturday.
A smaller party, the Armenian Revolutionary Federation, quit the ruling coalition and said it would also back the opposition leader.
Pashinyan urged his supporters to turn out in force on Sunday evening, saying in a video address: "Our fantastic rallies and meetings across the country have affected the situation in a powerful way."
Some analysts said they expected a number of Republicans to defect and give their votes to Pashinyan, sealing his victory.
"I am sure that at least six people from the Republican Party -- like rats from a sinking ship -- would vote for Pashinyan," said analyst Ervand Bozoyan.
Observers have expressed fears that the turmoil could destabilise the Moscow-allied nation which has been locked in a territorial dispute with Azerbaijan for decades.
Pashinyan met Sunday with Russian lawmakers, telling them his premiership would not threaten the South Caucasus country's close ties with Moscow.
Russian President Vladimir Putin earlier this week spoke by phone with the interim head of government.
One of the Kremlin's closest allies, Armenia hosts a Russian military base and is dependent on investments and aid from Moscow.
Russian border guards patrol Armenia's border with Turkey and Iran.
The United States on Saturday urged "good faith" in negotiations, with a State Department statement calling for "a resolution that reflects the interests of all Armenians."