Abe's resignation left the troubled LDP scrambling for a replacement. Almost all eyes immediately fell on former foreign minister and fellow conservative Taro Aso.

The principal officer of Asia Strategy Institute of Tokyo, Keith Henry said"Obviously, Taro Aso will be the front-runner mainly because everyone for the last six months have been saying he's the likely successor. Nobody thought he would be the successor so soon, but that's just the way it goes."

Taro Aso says the Liberal Democratic Party will choose Abe's successor quickly in order to avoid creating a political vacuum. Aso was expected to announce his candidacy later on Thursday.

By Thursday evening, Finance Minister Fukushiro Nukaga had declared he would run.

Other names in the list of successors include former finance minister Sadakazu Tanigaki and former chief cabinet secretary Yasuo Fukuda.

Some lawmakers petitioned for the return of Abe's predecessor Junichiro Koizumi, but Koizumi has reportedly refused pleas to join the race.