PASOK party president Fofi Gennimata and European Parliament deputy Nikos Androulakis are the two contenders headed into a second round for the leadership of a new center-left grouping being established in the country.
The second and final round comes next Sunday.
In the first round, Gennimata picked up 70,679 votes (42.76 percent), and Androulakis 41,955 votes (25.38 percent).
Athens Mayor Giorgos Kaminos was preferred by 22,226 voters (13.45 percent), while centrist Potami party leader Stavros Theodorakis came in fourth with 5,603 votes (9,44 percent). Another five contenders all received single-digit percentage points in terms of votes.
Election of the president of the nascent political party came via a popular vote, with more 210,000 people participating in the process after paying a nominal membership fee and showing some sort of ID.
