Complex sentence: Social Democratic Party organized an informal membership poll in August 2017 for electing the party's presidential candidate, with three candidates entering the race, MPs Maarit Feldt-Ranta, Tuula Haatainen and Sirpa Paatero.
Split into simpler sentences: Social Democratic Party will organize an informal membership poll in August 2017 for electing the party's presidential candidate. There are three candidates seeking for the candidacy, MPs Maarit Feldt-Ranta, Tuula Haatainen and Sirpa Paatero.