PODGORICA (Reuters) - Montenegro’s Prime Minister Milo Djukanovic emerged weakened on Monday from an election he had cast as a choice between NATO membership or subjugation to Russia.

Djukanovic, who has led the small Balkan state for a quarter of a century, faced an uphill task to assemble a coalition after a partial vote count suggested his Democratic Party of Socialists (DPS) would win 36 seats, five short of a majority in the 81-seat parliament.

Opposition parties appeared determined to form a rival coalition to eject Djukanovic, accusing him of treating the tiny country of 620,000 as a personal fiefdom where corruption and organized crime flourish.

The former Yugoslav republic is in the process of joining NATO, to the annoyance of Russia, which wants to retain influence in the Balkans and stop Montenegro and neighboring Serbia from escaping its orbit by joining the European Union.

Despite its small size, Montenegro’s Adriatic coastline gives it potential strategic importance and is a powerful draw for Russian tourists. Ubiquitous Russian-language billboards advertise new luxury properties for sale.

In a midnight address to supporters, Djukanovic said he would seek a coalition with the small Social Democracy party as well as statutory representatives of the Bosniak, Croat and Albanian ethnic minorities, which would give him a slender majority.

But opposition parties were reluctant to contemplate entering a deal with the man who had accused many of them of taking Russian funding in order to scupper his plans for NATO membership.

“The DPS has been defeated and we will now see whether it will succeed in using its alchemy to deliver a winning result,” said Miodrag Lekic, leader of the opposition Kljuc (“The Key”) alliance, which was on course for nine seats.

Djukanovic portrayed Sunday’s vote as a choice between peace, prosperity, deeper European integration and NATO membership under his leadership, and being reduced to a “Russian colony” under opposition parties, even though many also support joining NATO.

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Many say the choice between NATO and Montenegro’s traditional Russian and Serbian allies is artificial for a country whose economy has grown strongly on the back of Russian, Chinese and Italian investment in mining, energy and tourism.

“Corruption is like a cancer eating Montenegro inside, and that is why Djukanovic is about to win again,” said Andrija Djukic, 23, a student. “This was entirely unrelated to Russia or anything else.”

The Democratic Front, another opposition alliance, looked set to win 18 seats. Together, the opposition and ethnic minority representatives also looked potentially capable of cobbling together a fragile majority.

The election was marred by the threat of violence. Authorities placed in investigative detention 20 Serb citizens who were arrested as they entered the country in the early hours of Sunday morning on suspicion of plotting armed election night attacks. Six were released on Monday morning.