Sociologist Arnis Kaktins said that the fluctuations were minor compared to November and no significant conclusions could be made from them.
2018 will be an important year in Latvian politics with scheduled parliamentary elections due to take place in early October. The exact date is yet to be declared.
The Harmony party, currently sitting in the opposition in the Latvian parliament but controlling Riga City Council, now enjoys support of 20.7 percent of the electorate, up from 19.8 percent in November. Having often been referred to in the past as a "Russian party" or a party representing the interests of Latvia's large ethnic Russian minority, it has in recent months made a concerted effort to re-brand itself as a Social Democratic party. Harmony seems fairly certain to remain the largest single party in Saeima.
The popularity rating of the ruling Greens/Farmers, which had been moving up for the three previous months, decreased slightly in December but it is still the second most popular political party in Latvia, supported by 14.3 percent of voters, down one percentage point from November. It has an agrarian agenda and is popular with older voters.
The National Alliance ranks third with 7.3 percent of votes, up 0.3 percentage points from November. It is a grouping of right-of-center parties ranging from traditionalist conservatives to right-wing nationalists.
The opposition Latvian Alliance of Regions ousted the New Conservative Party from fourth place in December as the number of its supporters has increased to 3.6 percent from 2.4 percent.
The New Conservative Party, currently not represented in the Latvian parliament, has slipped down to the sixth place, as it is now supported by 3 percent of the electorate.
The center-right Unity party, which was triumphant at the last Saeima elections under then-Prime Minister Laimdota Straujuma has seen its fortunes disintegrate due to in-fighting. It now ranks fifth with just 3.5 percent support, having lost 0.3 percentage points of its rating in December, a less than ideal start for new leader Arvils Ašeradens' recovery plan.
The opposition For Latvia from the Heart is supported by 1.8 percent of voters, or by 0.3 percentage points less than in November.
The two outliers of the political scene - KPV LV and The Movement For! are each supported by 1.5 percent of voters, but while the former lost one percentage point, the latter improved its popularity rating by 0.3 percentage points.
Latvia operates a proportional representation system whereby a 5-percent electoral threshold needs to be reached to gain seats in parliament.
Nearly one quarter of voters are still undecided, the poll suggests, meaning there are plenty of votes still to fight for during ten long months of campaigning.