The Moderate Party, which had shot up by 3 percentage points in a similar survey in July, suffered a drop of 3 percentage points on Monday.
Party spokesman Kent Persson told the Aftonbladet paper that the fluctuating results only went to show that voters were still unsure ahead of September's national election.
Despite the Moderates' stumble, the governing Alliance crept 0.6 percentage points closer to the red-greens, which sat at 46.6 percent. The Alliance, meanwhile, earned 36.8 percent of the respondents' confidence.
The results saw the Liberal Party increase by 2.5 percentage points to 7.5 percent and the Centre Party increase by 0.4 percentage points to 5.2 percent. The Christian Democrats, meanwhile, raked in 4.3 percent of the responses.
Far above the rest were the Social Democrats, headed by Stefan Löfven, which pulled in 29.6 percent (compared to the second-placed Moderates with 19.8 percent).
The Left Party brought in 7.2 percent, the Greens 9.8 percent, and the Feminist Initiative 2.9 percent. The Sweden Democrats earned 11.6 percent of respondents' support.
The poll was carried out by United Minds for the Aftonbladet newspaper. Almost 1,300 people were interviewed between the 3rd and 10th of August, and were asked who they would vote for if the elections were today.