Armenia's acting head of government Karen Karapetyan on Friday rebuffed talks proposed by opposition leader Nikol Pashinyan, further escalating tensions after two weeks of protests.
Karapetyan's refusal to negotiate came after he spoke to Russian President Vladimir Putin by phone on Thursday.
Pashinyan, who has been leading the mass anti-government protests, defiantly declared himself the only suitable candidate for prime minister in the Moscow-allied country.
Armenia was plunged into crisis over the fate of veteran leader Serzh Sarkisian, who finally quit on Monday after a decade in power.
Pashinyan has issued an ultimatum to the authorities, saying he should be elected prime minister in a vote by lawmakers on May 1.
But a spokesman for Karapetyan dismissed Pashinyan's demands.
"The acting prime minister believes that negotiations where one side dictates the agenda and the other cannot do so, cannot be considered negotiations," the spokesman said Friday.
Instead, Pashinyan should discuss ways to tackle the crisis together with all political forces, the spokesman quoted Karapetyan as saying.
Deputy speaker of parliament, Eduard Sharmazanov, called Pashinyan's demand to negotiate with the ruling party in front of the press "absurd", saying this would play into the hands of Yerevan's foes Azerbaijan and Turkey.
"Not only will protesters and the opposition be watching, but also (Azerbaijani president) Aliyev and (Turkish president) Erdogan," Sharmazanov said.
Pashinyan accused Sarkisian's ruling Republican Party of seeking to increase the turmoil and urged his supporters to stage new rallies to pile pressure on Karapetyan.
"The fact that Karen Karapetyan refused to negotiate means that the Republican Party is in total disarray," Pashinyan told reporters on Friday.
"The question is, does the Republican Party want to settle the crisis or not?" he said, suggesting the ruling elites could not conduct free and fair elections.
"We should have a guarantee that an election will be really free, really transparent, really democratic," he said in English, wearing his trademark camouflage T-shirt.
He earlier told supporters he needed to become the next leader to oversee snap parliamentary elections and clean up the political system.
"If I am not elected prime minister, then Armenia will not have a prime minister at all," the 42-year-old former newspaper editor said.
The crisis erupted over Sarkisian's election as prime minister by parliament last week after a decade as president. He resigned on Monday on the 11th day of the protests.
The opposition has accused Sarkisian's party of clinging onto power after he failed to tackle widespread poverty, corruption and influential oligarchs close to the authorities.
But the ruling party has a majority of seats in parliament and Pashinyan does not have enough support from lawmakers to get elected.
Pashinyan has called a halt to protests in Yerevan to give demonstrators some rest after two weeks of nearly non-stop rallies, saying people should return to the streets on Sunday.
But on Friday he headed a column of cars carrying hundreds of his supporters from Yerevan to Gyumri, the second largest city north of the capital where he planned to hold a rally later Friday. The city also hosts a Russian military base.
An AFP reporter travelling with the protest leader said villagers on the way gave Pashinyan a hero's welcome, offering him traditional bread and salt as well as fresh fruit.
Another rally is planned for Saturday in the third largest city of Vanadzor.
A previous attempt at talks between the opposition leader and the acting prime minister collapsed earlier this week.
Observers have warned the crisis could destabilise the South Caucasus nation, which is involved in a decades-long territorial dispute with Azerbaijan.
A number of top Armenian officials held talks with Russian Foreign Minister Sergei Lavrov and other officials in Moscow on Thursday.
Putin has stressed the importance of the May 1 vote, the Kremlin said after his phone talks with Karapetyan.
Analysts said the situation in Armenia was hugely unpredictable.
"It's impossible to tell if the country will come out of this chaos on May 1," analyst Ervand Bozoyan said, adding that frantic negotiations were under way among political parties.
Another analyst Stepan Safaryan said that while the core of the Republican Party has no intention of backing down, it was possible that some of its lawmakers would vote for Pashinyan.