The pro-Kremlin Harmony party looked set to hold the balance of power in Latvia, following a general election on Saturday, with an exit poll showing it topping the vote ahead of liberals.

A public TV exit poll showed Harmony had a 19.4% vote share, while the liberal pro-EU, pro-Nato For Development was in second place with 13.4%, ahead of the rightwing National Alliance on 12.6%.

Populists, who could help Harmony form a coalition, followed closely behind. The New Conservative party was on 12.4% and KPV LV showed 11.5%.

The Greens and Farmers Union of the prime minister, Māris Kučinskis, managed 9.7%.

“No coalition combination is possible without Harmony that would appear able and stable,” the Harmony chairman and Riga mayor, Nils Ušakovs, told the Leta agency. “Otherwise, you could have a coalition of xenophobes to gay rights supporters, and such a government would stick together for two or three weeks.”

Popular with Latvia’s ethnic Russian minority, which makes up about a quarter of the country’s 1.9 million population, Harmony, formerly allied with United Russia, the party of the president, Vladimir Putin, won the largest number of votes in the last three elections. However, it never entered government as it failed to attract coalition partners.

The final results of the vote are expected early on Sunday, with coalition talks to follow while the current parliament keeps working until November.

The vote was tarnished by a hacker attack on the Draugiem.lv social network, second in popularity only to Facebook in the Baltic state, which displayed a pro-Russian message.

“Comrades Latvians, this concerns you. The borders of Russia have no end,” it said in Russian, followed by images of unmarked Russian soldiers in green uniforms annexing Crimea, Russian tanks parading in Moscow and a smirking Putin.

Turnout in the vote was 53.99%, according to the election website.

Analysts predicted Harmony, which has signed on some high-profile ethnic Latvians as their frontrunners, might join forces with populists to govern.

KPV LV, a populist party led by former stage actor Artuss Kaimiņš, is a potential coalition partner.

And the party’s candidate for prime minister, lawyer Aldis Gobzems, recently suggested they were open to working with other parties.

“KPV LV can work with anybody, we don’t have any red lines regarding any other political force,” Gobzems said during a TV24 debate.

• This article was amended on 12 October 2018 after a representative of Nils Ušakovs contacted the Guardian to state that Ušakovs had said “...a coalition of xenophobes to gay rights supporters” not “...a coalition of xenophobes and gay rights supporters...”



