Members of Japan's ruling Democratic Party (DPJ) will vote for a new leader Friday, after party president and Prime Minister Yukio Hatoyama resigned Wednesday.

Finance Minister Naoto Kan, who has announced he will run for the position, is considered a frontrunner while Foreign Minister Katsuya Okada and Transport Minister Seiji Maehara are also hopefuls.

Naoto Kan, two-time DPJ leader

Also deputy prime minister, Kan, 63, is a veteran in the DPJ. He co-founded the party in 1996 and has led the party twice.

Born on October 10, 1946 in Yamaguchi Prefecture, Kan was a graduate of the Tokyo Institute of Technology. After being engaged in civic activities in the 1970s, he was first elected to the lower chamber of Japan's Diet in 1980 as a member of a small opposition party.

In September 1996, Kan co-founded the DPJ with Hatoyama and served as the party's co-president. In September 1997, Kan was elected as party president and reelected in January 1998. He remained in the position until September 1999, despite the DPJ's merger with three other smaller parties.

From September 2000 to September 2002, Kan served as secretary-general of the DPJ. In December 2002, he was elected again as party president until he resigned in May 2004.

Kan became deputy prime minister in September of 2009 in the Hatoyama administration and has been finance minister since January 2010.

Katsuya Okada, veteran politician

Born in Yokkaichi in 1953, Okada was the second son of Takuya Okada, founder of Japanese retail giant AEON Group. He graduated from the University of Tokyo with a law degree and also studied at Harvard University.

In 1990, he was first elected to the House of Representatives as a member of Liberal Democratic Party (LDP), but he quit the party in 1993 to join the DPJ. He served as the DPJ's general-secretary from 2002 and was elected president in 2004.

In September 2009, Okada became foreign minister in the Hatoyama administration.

Okada is well known for his expertise in economic, diplomatic and administrative policies. He believes the Japan-U.S. alliance should be the foundation of Japan's foreign policy but also stresses the importance of developing ties with Asian countries.

Seiji Maehara, expert in national security and defense

Maehara was born in April 1962 in Kyoto and attended the Law Faculty of Kyoto University, where he majored in international politics.

He was first elected to the House of Representatives in 1993 as a member of the Japan New Party of Morihiro Hosokawa. In 1998, he joined the DPJ and served as its vice president for some time.

He served as the DPJ president from September 2005 to March 2006.

In September 2009, he assumed the office of Minister of Land, Infrastructure, Transport and Tourism in the Hatoyama administration.

Maehara is known for his expertise in national security and defense and is a notable advocate for revising Article 9 of the Constitution of Japan, which prohibits Japan from taking offensive military action.