South Korea will hold a presidential election on May 9 to replace impeached leader Park Geun-hye, who was dismissed last Friday over a corruption scandal, the Yonhap news agency has reported.
Prime Minister Hwang Kyo-ahn, who has also been acting president since December, said earlier he would not run in the election.
Hwang became acting president when parliament impeached Park in December and later emerged in opinion polls as a top conservative candidate, though he had never declared an intention to run.
Prosecutors said on Wednesday that they planned to summon and question Park next week.
Park lost her presidential immunity from prosecution after the Constitutional Court ruled on Friday to formally end her rule over allegations she colluded with a longtime confidante to extort money from businesses and allowed her to pull government strings from the shadows.
Prosecutors said they told Park's lawyer they would summon her next Tuesday as a suspect. No further details were provided.
Dozens of high-profile figures including some top Park administration officials and Samsung heir Lee Jae-yong have already been indicted.
Park could also face extortion, bribery and other criminal charges. She has denied any legal wrongdoing and expressed defiance toward her corruption allegations.
"Although it will take time, I believe the truth will certainly come out," Park said after leaving the presidential Blue House on Sunday.
Her comments raised worries about a deepening of the national divide over her fate. Three people died and dozens were injured in violent clashes between Park's supporters and police afterf Friday's ruling.