Opposition leader Antti Rinne looks likely to be re-elected as chair of the Social Democratic Party, which leads public opinion polls.
A new poll by Lännen Media suggests that Rinne enjoys the support of the slim majority of SDP delegates, at 50.9 percent. His two challengers, Timo Harakka and Tytti Tuppurainen, have 24.8 percent and 7.1 percent support respectively. Tuppurainen only announced her candidacy on Wednesday.
Lännen Media reached just under 300 of the 500 party delegates for the survey.
The SDP will hold a leadership vote at its party congress in Lahti on February 4.
Rinne must secure at least 251 votes for re-election. Lännen Media projects that he currently has about 256 backers, followed by challenger Harakka with 123. Rinne could win a new term outright in the first round of voting.
The 54-year-old Rinne served as chair of three labour unions between 2002 and 2014, when he was elected as SDP leader. He then served as finance minister for just under a year. If his party retains its strong standing in opinion polls, he could be a contender as Finland's next prime minister after the 2019 elections.
The three candidates begin a national debating tour in Kuopio on Saturday.