According to the latest poll conducted by SKDS for Latvian Television, Harmony is still in the lead with 14% support in early April, though its figure has fallen from 15% a month before.
The liberal-centrist Development/For! alliance is in second place with 10.9% of the vote, just ahead of the center-right New Unity party of Prime Minister Krišjānis Kariņš on 10.8%.
The right-conservative National Alliance enjoys a 0.9% boost on April's figure in fourth spot with 9% of voter support and in an even larger surge the Kremlin-friendly Latvian Russian Union saw its support rise by 1.9% to 6.9%, suggesting that perhaps some Harmony voters may have switched their allegiance.
Meanwhile the left of center Progressives have 4.3% - coming in ahead of two parties with seats in Saeima, the Greens and Farmers Alliance (3.8%) and the New Conservatives, who record a surprisingly small figure of 3.2% despite being one of the largest parties in the ruling government coalition.
The remaining eight parties contesting the elections muster only 5% between them.
As ever with such polls in Latvia, the joker in the pack is the level of "don't knows" and those saying they will not participate at all, which when combined account for nearly a third of all respondents (32%).
The data was based on a survey of 918 Latvian citizens conducted between April 29 and May 6.
As previously reported by LSM, European Parliamentary elections take place in Latvia on May 25. You can read about the various party offerings in our preview feature and you can find out more about the elections themselves at the website of the Central Electoral Commission.
16 parties will contest the elections. Latvia has just eight mandates in the European parliament.