According to preliminary results released by the party, Blinkeviciute received approximately 56 percent of the vote while MEP Juozas Olekas was second with about 44 percent.
More than 7,900 party members turned out for the election.
The party’s commission in charge of the chairperson election will endorse the final results of the vote on May 14. The chairperson-elect will take up her duties on May 29, the day of the upcoming party’s congress.
Blinkeviciute, a lawyer, spent many years working in the Ministry of Social Security and Labor, including eight years as the minister.
She has been a member of the SDPL since 2006 and its deputy chairperson since 2009.
Since 2009, she has been a member of the European Parliament.
In January, MP Gintautas Paluckas resigned as the party's chairman following the criticism over the party’s poor performance in the recent general elections.
The SDPL is the largest party in Lithuania, having over 16,500 members. It has 13 seats in the Lithuanian Seimas.