YEREVAN, Armenia (AP) — Thousands of protesters converged on the parliament building in Armenia's capital Wednesday to push for the resignation of the ex-Soviet nation's prime minister over his handling of the fighting with Azerbaijan over Nagorno-Karabakh.

Nikol Pashinyan's opponents are angry at a peace deal that ended six weeks of fighting over the separatist region but saw Azerbaijan take over wide areas that have been controlled by Armenian forces for more than a quarter-century.

Armenia's opposition parties gave Pashinyan an ultimatum to resign by Tuesday, but he has ignored the demand, defending the peace deal as a bitter but necessary move that prevented Azerbaijan from overrunning the entire Nagorno-Karabakh region.

About 15,000 protesters marched through downtown Yerevan to the parliament building, chanting “Nikol go away!”

The opposition has been pushing for Pashinyan's resignation since the Russia-brokered peace deal took effect on Nov. 10. Protests have grown over the past days, with demonstrators blocking traffic in various sections of the capital, and also rallying in other cities.

The Armenian Apostolic Church and all three of the country’s former presidents have joined the demand for Pashinyan to step down.

Undeterred, the prime minister told lawmakers in parliament Wednesday that the nation needs consolidation in the current difficult period. “Voices of different groups mustn't be mistaken for the people's voice,” he said.

Nagorno-Karabakh lies within Azerbaijan but has been under the control of ethnic Armenian forces backed by Armenia since a separatist war there ended in 1994. That war left Nagorno-Karabakh itself and substantial surrounding territory in Armenian hands.

In 44 days of fighting that began in late September and left more than 5,600 people killed on both sides, the Azerbaijani army forged deep into Nagorno-Karabakh, forcing Armenia to accept the peace deal that saw Azerbaijan reclaim much of the separatist region along with surrounding areas.

Azerbaijanis have celebrated it as a major victory, and the country is set to hold a massive military parade Thursday — to be attended by visiting Turkish President Recep Tayyip Erdogan. Turkey strongly backed Azerbaijan during the conflict, which it used to expand its clout in the region.

Vladimir Isachenkov in Moscow contributed to this report.