Falling 4.3 per cent since the previous Demoscop poll carried out one month ago, the Social Democrats are now registering 23 per cent, their lowest showing since records began 26 years ago.
The fall confirms the party's recent poor showing in similar polls.
Combined, the Social Democrats, the Left Party, and the Green Party attracted 35.7 per cent support, while the four centre-right parties - the Moderates, Christian Democrats, the Centre Party and Liberals - enjoyed 42.6 per cent.
The far-right Sweden Democrats were effectively unchanged on the previous poll at 18.1 per cent, making it Sweden's third largest party once again.
The poll was conducted with 1,256 interviewees between January 26 and February 2.