After Masuzoe announced his resignation in June 2016, Koike announced her intention to run in the election for his successor. Koike stated that she would run "as an LDP lawmaker" but did not obtain the approval of the Tokyo LDP chapter before announcing her candidacy. The LDP officially endorsed Hiroya Masuda, and its Tokyo chapter issued a notice that any members supporting Koike would be punished. Nonetheless, several prominent LDP politicians continued to back Koike, while senior leaders such as Shinzo Abe refrained from making speeches in support of either candidate.