With a quarter of voters remaining undecided on the eve of the election, according to independent polling firm SKDS, the result is still wide open.
"This is breaking our agreement with North Atlantic Treaty Organisation, of which Latvia is a member since 2004, he adds".
The Russian minority accounts for about 25 percent of Latvia's almost 2 million people, a legacy of almost 50 years of Soviet occupation that ended in 1991.
Harmony wants to remain in the European Union and North Atlantic Treaty Organisation but have closer economic ties with Russia and only cancelled a cooperation agreement with Putin's United Russia party a year ago.
The party has won the largest number of votes in the last three elections, and did not enter government only because it failed to attract coalition partners.
But this time around that could change.
Hackers targeted the Draugiem.lv network, second in popularity only to Facebook in the Baltic state, with a pro-Russian message.
But it was subsequently occupied by Nazi Germany and after them by the Soviet Union for almost half a century until 1991.
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I wanted to prove to him I can do what he said I couldn't'. "He has chosen to have a year out, he will not dive in again before that is over".
Including both the Greens and Farmers, and New Unity would create a more comfortable 61-seat majority, but a five-party coalition would be harder for a prime minister to control.
"Now. voters want new faces: the current ministers can not offer anything entertaining. This is where the populism finds its niche", says the political scientist Filips Rajevskis.
Therefore numerous coalition combinations look potentially possible.
Voters are choosing from a field of more than 1,400 candidates and 16 parties Saturday to fill Latvia's 100-seat parliament, or Saeima. The National Alliance would have thirteen and the Unit, renamed the New Unit, could not cross the eligibility threshold of 5%. For example a coalition containing the New Conservatives, National Alliance, For Development/For! and the Greens and Farmers Union would hold 53 seats.
Harmony meanwhile has signed on some high-profile ethnic Latvians as their frontrunners, and is on track to come out ahead with at least 28 seats.
Other parties have previously formed coalitions to keep Harmony out of government.
Final results of the election are expected on Sunday and coalition talks could take several weeks. Political analyst Marcis Bendiks said Harmony's campaign promise to cut defence spending to one percent of GDP went against North Atlantic Treaty Organisation agreements.
But dissatisfaction with Latvian politicians, widely seen as corrupt and inefficient, has seen the government parties lose voters to KPV LV, a populist party that has promised a fresh and more efficient government.