More than 90 percent of the country's 1.8 million voters supported the name-change in Sunday's non-binding referendum, but the opposition said the low turnout rendered the referendum "deeply unsuccessful."
Macedonia's prime minister vowed to push ahead with changing the country's name after voters approved it in a referendum, but the outcome looked uncertain on Monday as opponents said low turnout made the result void.
Macedonian voters backed the plan to rename the country aimed at ending a decades-long spat with Greece and unlocking a path to NATO and EU membership, with the West welcoming the result.
With ballots from 93 percent of polling stations counted, 91.3 percent of votes cast on Sunday favoured the name changing to North Macedonia, compared to 5.7 percent opposed, according to the electoral commission's official count.
However, only a third of the 1.8 million-strong electorate voted.
The ballot was closely watched by Greece, which said it "remains committed" to its June agreement with Skopje under which Athens would drop its objections to Macedonia joining the EU and NATO in return for a change of name.
TRT World's Iolo ap Dafydd reports from Skopje.
'NATO's door is open'
Greek Prime Minister Alexis Tsipras expressed his support for his Macedonian counterpart in a telephone call in which he hailed the "determination and courage" of Zoran Zaev to "complete the implementation of this agreement," a government source told AFP.
The European Union urged all sides to respect the result and NATO head Jens Stoltenberg said on Twitter it was a "historic opportunity," adding, "NATO's door is open."
Washington also welcomed the outcome, with the State Department urging lawmakers "to rise above partisan politics and seize this historic opportunity to secure a brighter future for the country as a full participant in Western institutions."
The non-binding referendum on renaming Macedonia needs to be ratified in parliament by a two-thirds majority and also given the stamp of approval by the Greek Parliament.
Zaev and his coalition partners from the ethnic Albanian minority will need at least a dozen MPs from the opposition to back the move.
Lack of enthusiasm
"MPs now have an obligation to make Macedonia a better place for all of us," Zaev told reporters late on Sunday.
But the right-wing opposition VMRO-DPMNE party said the low turnout made the referendum "deeply unsuccessful" with party leader Hristijan Mickoski telling reporters the "government lost its legitimacy."
However, the party that ruled Macedonia for a decade until 2017 was split during the referendum campaign. Mickoski did not vote, but several MPs took part in the polls, including the party's Vice President Mitko Janchev.
Zaev said that if he failed to obtain the required majority in parliament to back the name deal, he would call early elections, two years after the last ones.
The vote is an emotional moment for a country that has struggled for recognition of its name since 1991, when the former Yugoslav republic declared independence.
At the time, Athens kicked up a major fuss, accusing Skopje of stealing the name of its own northern province, which is also called Macedonia.
The dispute dives deep into history with both countries vying to lay claim to Alexander the Great's ancient empire of Macedon, which spanned their territories.
Zaev had billed the referendum as a painful but "historic" opportunity to break a 27-year-old stalemate.
The June deal, however, was openly opposed by Macedonia's President Gjorge Ivanov, who is allied with the nationalist opposition and had supported calls for a boycott of the referendum.
Few Macedonians are enthused about the new name, saying they have been unfairly bullied by Greece.
"I am not happy, and I do not know anyone who likes this deal," said 55-year-old Danica Taneska, who voted "no."
But a desire to anchor their future to the West — and the economic prosperity that it could bring — has been a driving force behind the "yes" vote in one of Europe's poorest nations.
Greece watching closely
The referendum is not binding, but a "yes" majority gives parliament a political mandate to change the constitution.
Europe and the US have campaigned hard for the deal, with many leaders passing through Skopje this month to urge Macedonians to seize the "historic" opportunity.
NATO has already issued an invitation — on hold until the deal passes — while EU accession talks are scheduled to begin next year.
The West is keen to have another foothold in the Western Balkans, a region where Russia, which is opposed to NATO expansion, has historically had influence.
At home, those in favour of the deal say a desire for an EU future is helping bind ethnic Macedonians with the Albanian minority, who are broadly pro-West.
While Macedonia avoided the full-scale inter-ethnic wars that rippled across the region during the collapse of Yugoslavia, it was roiled by an Albanian insurgency in 2001 that left more than 100 dead.
A peace deal was reached later that year granting Albanians more political rights, but tensions have remained.