YEREVAN -- Tens of thousands of people have attended a mass rally called by Armenian opposition leader Nikol Pashinian in Yerevan aimed at showing his popular support on the eve of a parliamentary vote on whether he should be prime minister.

As he took to the stage at the beginning of the rally on Yerevan's central Republic Square, Pashinian was joined by Armenian-American rock star and activist Serj Tankian, who is the lead singer of the alternative-metal band System of a Down.

Tankian, who has offered his support for Pashinian's protest movement, addressed the cheering crowds in Armenian. "You managed to turn your anger and despair into a positive movement," he told the crowd.

Then, in an emotionally charged moment, he sang a fragment from a popular Armenian patriotic song, Bari Aragil (Kind Stork), accompanied by the crowds.

During the short rally, Pashinian said he had "a 95 percent chance" of winning the prime-minister nomination in parliament on May 8 and reiterated his call for his supporters to show up again on Republic Square at 11 a.m. to celebrate "an epochal victory."

Tankian was welcomed earlier at the Yerevan airport by Pashinian and his supporters. During their drive into Yerevan, Pashinian and Tankian were greeted by thousands of people who lined the streets leading to Republic Square.

Pashinian has threatened to stage another general strike if the ruling Republican Party (HHK) does not elect him as prime minister on May 8, after tens of thousands of Armenians on May 2 heeded his call and brought much of the country to a standstill.

After leading a wave of protests throughout the South Caucasus country over the past several weeks, Pashinian appears to be on the verge of a dramatic rise to the prime minister's post.

The antigovernment protests forced HHK leader and longtime former President Serzh Sarkisian to step down as prime minister just days after he was elected to the position by parliament.

Sarkisian had been president since 2008. Term limits forced him to step aside last month.

However, the HHK-dominated parliament quickly appointed him as prime minister, a switch made possible by constitutional changes that weakened the presidency while bolstering the prime minister's powers.

The move prompted thousands to heed Pashinian's call to take to the streets, accusing Sarkisan of clinging to power and voicing concern that the new system could have allowed Sarkisian to remain Armenia's leader indefinitely.

After failing in an initial parliamentary vote on the next prime minister, Pashinian was officially nominated on May 3 for a second time as the only candidate for the post by his Yelk faction and allied opposition parties.

Pashinian secured the backing of 41 lawmakers in the 105-seat parliament for his nomination for the May 8 vote.

The HHK holds 58 seats, but it has said it will vote for whichever candidate is backed by at least one-third of the lawmakers.

During the May 7 rally, Pashinian told the crowds that he received assurances from the Armenian Revolutionary Federation (Dashnaktsutyun) and the Tsarukian Alliance parliamentary factions that they would vote for the "people's candidate" and that some members of the HHK faction would also vote for "the candidate nominated by you."

Under Armenia's constitution, if a prime minister is not elected in the second vote, parliament will be dissolved and early general elections would be held with the HHK-led acting government in charge of the electoral process.

Pashinian has said elections run by the HHK would not be fair, and he has called for the party to give up power.

However, Pashinian told journalists on May 7 that he would not seek revenge against his political adversaries if elected.

"There will not be a vendetta. In Armenia, the page of political and economic persecution has been closed," he said.

He also told RFE/RL that he would not accept the presence of oligarchs in his government if elected prime minister on May 8.

"I can assure you that there will not be oligarchs in government," Pashinian said, adding, "There will be no monopolies in our economy if I am elected."

Separately, Ararat Mirzoian, one of Pashinian's close aides, told RFE/RL that, if elected prime minister, the opposition leader will strive to break up economic monopolies, boost competition, and separate business from government.

However, wealthy business people linked to the outgoing Armenian government will not risk losing their assets once Pashinian is appointed, Mirzoian said.

In comments to reporters on May 5, Pashinian vowed that he would call snap elections once in office, but only when he was "convinced they would be legitimate and transparent."

"My team and I are considering a few scenarios for holding the snap election,” he said, adding, without details, that "we will have to amend the election code for this purpose."

With reporting by TASS and AP