“If developments continue, this party won’t exist in 10 to 15 years,” she said to the labor organization Unionen in Gothenburg on Wednesday, according the Göteborgs-Posten newspaper.
The Social Democrats lost 19,000 members last year. The 16 percent drop is the largest in more than 10 years.
At the close of 2007, the party had a total of 101,158 members, compared with 120,091 one year earlier.
Membership has been cut in half since the 1990s.
Government parties also dropped thousands of members last year.
“The problem for all political parties can be illustrated by the fact that the national organization of pensioners (PRO) has more members than all of the political parties combined,” said Sahlin, who maintains that difficulties in recruiting new members and age demographics are facts of life.
“Just the fact that I am included among the younger members of the party says quite a lot,” said the 51-year-old party leader.