SKOPJE -- Macedonian President Gjorge Ivanov has said he won't sign a deal with Greece on the former Yugoslav republic's name, saying it violates the country's constitution.
Ivanov made the announcement on June 13, a day after the Macedonian and Greek prime ministers announced they had reached an agreement to name the country Republic of North Macedonia, or Severna Makedonija in Macedonian.
Under the accord, its language will be Macedonian and its people known as Macedonians or citizens of the Republic of North Macedonia.
"My position is final and I will not yield to any pressure, blackmail, or threats. I will not support or sign such a damaging agreement," Ivanov told a news conference.
Later in the day, about 1,000 people gathered in front of the parliament building in Skopje, calling for Prime Minister Zoran Zaev's resignation.
The demonstrators were holding Macedonian flags and chanting slogans such as "Zaev is a traitor."
Skopje and Athens have recently stepped up United Nations-brokered negotiations to resolve their 27-year name dispute, which dates back to 1991 when Macedonia peacefully broke away from Yugoslavia, declaring its independence under the name Republic of Macedonia.
Greece had objected to the name Macedonia, fearing territorial claims on its eponymous northern region.
Because of Greek objections, Macedonia was admitted to the UN under a provisional name, the Former Yugoslav Republic of Macedonia.
Greece, an EU and NATO member, has also cited the dispute to veto Macedonia's bid to join the two organizations.
But Ivanov said that Macedonia's possible future membership of the EU and NATO was not enough to sign such a "bad agreement," which the Macedonian president said gave too many concessions to Greece.
Zaev hailed the agreement as historic, adding, "There is no way back."
Greek Prime Minister Alexis Tsipras spoke of "a great diplomatic victory but also a great historic opportunity."
European Council President Donald Tusk and NATO Secretary-General Jens Stoltenberg issued a statement on June 13 welcoming the deal and expressing hope that "this unique opportunity to relaunch the wider Western Balkan region's European and Euro-Atlantic integration will not be wasted."
"This agreement sets an example for others on how to consolidate peace and stability across the region," the joint statement added.
The deal is expected to be signed by the Macedonian and Greek foreign ministers this weekend.
Macedonian lawmakers would then vote on it, and if it is approved, Ivanov's signature would be needed.
If he does not sign, the agreement goes back to parliament for a second vote, and the president would then have to sign off on the accord if it passed.
The deal will also go to a referendum in Macedonia in the fall.
The Macedonian and Greek prime ministers' efforts to forge a deal has faced strong dissent, with opponents staging large protests on both sides of the border.