Macedonia's four top politicians failed Monday to resolve the country's political crisis — and the opposition Social Democrat leader suggested the impasse would not be broken until the conservative government resigns and a caretaker regime organizes a fair election.

But Prime Minister Nikola Gruevski made it clear at a pro-government rally Monday evening that he would not step down.

"Our message to them is that we will not retreat," Gruevski told the crowd of tens of thousands in Skopje, the capital. "Those people are seeking my resignation without the people's will."

Macedonia faces one of its deepest political crises since gaining independence from Yugoslavia in 1991, stemming from opposition claims that the government illegally wire-tapped 20,000 people. Monday's talks, organized by Western diplomats, were attended by Gruevski, Social Democrat leader Zoran Zaev and two ethnic Albanian political leaders.

On Sunday, tens of thousands held an anti-government protest outside the government building in Skopje. Hundreds remained there Monday.

"We are not leaving this place until the government falls. Because we love this country (the government) has stolen. Because we want the democracy they killed. Because we love our children, whom they corrupted," said opposition supporter Pande Josevski.

The political crisis stems from Zaev's release of a cache of wiretapped conversations that appear to reveal corruption at the highest levels of government. He claims Gruevski was behind the wiretaps. Gruevski, who has won successive elections since 2006, rejects the accusations and accuses Zaev of participating in a coup plot backed by foreign spy agencies.

"Macedonia does not need a political establishment at the disposal of foreign intelligence services," Gruevski said at the Monday rally in front of the parliament building.

Compounding the crisis, a group of armed ethnic Albanians fought a gunbattle with Macedonian police on May 9 in a northern border town, leaving 18 people dead — 10 gunmen and eight police.

In Brussels, NATO Secretary General Jens Stoltenberg said Macedonians should work to de-escalate the conflict.

"The important thing is to avoid more violence, to make sure that the democratic institutions are developed and that a rule of law is implemented," Stoltenberg said.

The European Parliament has invited Gruevski and Zaev to Strasbourg, France, for talks Tuesday to resolve the crisis.