His brother Yukio Hatoyama, also a politician and leader of the rival Democratic Party of Japan, became the country's Prime Minister in September 2009 following a landslide victory in the August 2009 election.

Divisions between the brothers eventually led him to leave the DPJ in 1999, and he re-joined the LDP in 2000 after running unsuccessfully for the seat of the Governor of Tokyo.

[3] In a dispute with Asō over a possible replacement of Japan Post Holdings president Yoshifumi Nishikawa Hatoyama resigned on 12 June 2009.

He came under criticism from opponents to capital punishment such as Amnesty International Japan for his attitude, which said that he was trying to avoid accountability as well as showing disregard for human rights.

[7] In October 2007, during a news conference, Hatoyama attempted to justify plans to fingerprint and photograph all foreigners at immigration by claiming that an unidentified "friend of a friend", who is an Al-Qaeda terrorist involved in the 2002 Bali bombings, was able to sneak in and out of Japan repeatedly over the following years using different passports and wearing a fake moustache.

He also issued a statement denying any connections to members of Al-Qaeda, as well as apologising to Prime Minister Fukuda for the confusion he caused.