The centre-left coalition claimed 49.3 percent support in the new Sifo poll for May with the government Alliance on 46.2 percent.
The poll indicates that the key to centre-left success in the September election remains firmly with the Green Party who had the backing of 10.7 percent of votes in the May poll, up from 9 percent in April.
Support for the centre-left coalition remained especially strong among women, with the backing of 52.7 percent of female voters, with the Green Party claiming 13.3 percent.
The Alliance parties enjoyed greater support among those in work, among whom it is now a dead heat between the blocs. The May poll showed that the Alliance had lost some of its lead among pensioners.
The Swedish electorate is also increasingly split according to geography with the centre-right enjoying a 15.1 percentage point lead in the major cities, up from 8.1 points in April.
The Social Democrats have the backing of only 22.4 percent in the major cities, with the budget proposal presented on May 3rd impacting support negatively, Sifo writes in a statement.
Overall the Social Democrats claimed the support of 34.3 percent (34.1), the Left Party 4.3 (5.4), and the Green Party 10.7 percent (9).
The Moderates gained slightly to 30.9 percent (29.8), the Centre Party polled 5.1 percent (4.9), the Liberal Party (Folkpartiet) 6.7 percent and the Christian Democrats came in at 3.5 percent – under the 4 percent threshold for parliamentary seats.
The far-right Sweden Democrats dropped back to 3.5 percent in a month where the focus of the political debate has shifted firmly to the main political blocs.
Sifo interviewed 1,917 people between May 3rd and May 11th, after the presentation of the centre-left coalition budget, but before the full effects of the Greek debt crisis had had an impact.