Mr Gruevski opposes Greek attempts to have the country's name changed
Prime Minister Nikola Gruevski has claimed victory for his centre-right party in Macedonia's snap election, which was marred by ethnic violence.
With nearly all votes counted, he predicted his party, which campaigned for EU and Nato membership, could take an overall majority in parliament.
Mr Gruevski also voiced regret at violence in ethnic Albanian areas.
The poll was called after Greece blocked Macedonia's Nato admission in a dispute over the country's name.
Macedonia is also the name of a northern region of Greece.
Mr Gruevski's VMRO-DPMNE party has promised not to change the name of the country in the face of Greek pressure.
Election officials said with more than 97% of votes counted, the prime minister's party had about 47% - more than twice the support for the Social Democrats, who had taken 23%.
Police spokesman on violence surrounding Macedonia's election
If the figures were confirmed, "we will have more than 60 seats in the [120-seat] parliament," he said at a press conference at VMRO-DPMNE headquarters in Skopje.
In the Albanian stronghold of Aracinovo at least one person was killed and more than 20 were arrested following shootings between rival parties or with the police, and election officials closed a number of polling stations amid reports of intimidation and fraud.
Ethnic Albanian rebels fought an insurgency in 2001, demanding more rights for their community, which makes up about a quarter of Macedonia's population - but now the two main ethnic Albanian parties are bitter rivals.
"In most parts the vote was fair and democratic, but sadly in one part there were irregularities," Mr Gruevski said.
"I will do everything in my power to have a re-run there so each and every MP is elected fairly."
The worst unrest was in the town of Aracinovo
This troubled polling day could harm the country's chances of Western integration, the BBC's Helen Fawkes reports.
The European Union's executive, the Commission, has said it is very concerned by the situation.
Denis MacShane, an MP leading a UK observer delegation to the polls, called the violence and disruptions "an assault on democracy unacceptable in today's Europe".
"No government can be formed as a result of this election," he said.
"New polls must be organised in all the districts where violence, intimidation and stuffing of ballot boxes have taken place."
Officials said voting was suspend in 22 polling stations - 1% of the total - and the vote would be repeated in those areas within two weeks.
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