The poll reflects several others in recent weeks showing a red-green slide.
On Thursday Statistics Sweden released its twice yearly poll, giving the opposition a 6 point lead over the government. It was based on a sample three or four times those of other polls, but analysts point out it was largely conducted before the opposition presented their shadow budget, which is seen as having alienated many voters because of proposed tax increases.
On the other hand, the Sifo poll is not all good news for the government, as it also indicates that two of the coalition parties, the Center and Christian Democrats, could fail to reach the 4 percent threshold for representation in parliament.
It also shows the anti-immigrant Sweden Democrat party would gain representation for the first time.