According to a YouGov poll, the party received 25.2 percent support from Swedish voters, while the Swedish Social Democratic Party got 23.4 percent and Moderate Party received 21 percent support.
The poll also found that as many as 46 percent of voters believed migration and refugees to be a key political issue for Sweden.
"This is not very surprising. We have been witnessing this tendency of Sweden Democrats for a long time. The reason for this is simple," Soren Holmberg of Gothenburg University told the Metro newspaper, referring to the poll’s results on migration.
According to Holmberg, Sweden has recently seen a number of crimes linked to migration.
Political expert Stina Morian believes that the poll took place "in special circumstances," as two Swedes were stabbed in an Ikea store by undocumented Eritrean immigrants earlier this month.
"The atmosphere online and in the media was full of hate. I believe that this is a combination of those long debates that we had been having for a long time," Morian told the Metro.
The YouGov poll comes amid an ongoing Europe-wide refugee crisis, with Sweden providing temporary residence to thousands of refugees from war-torn Syria.
The UN Refugee Agency documented 137,000 refugees crossing the Mediterranean Sea into Europe in the first six months of 2015, compared to 75,000 during the same period in the previous year.
