Ms. Park’s presidential powers have been suspended since Dec. 9, when the National Assembly voted for her impeachment, saying that she took bribes and committed a variety of other offenses. She is now on trial at the Constitutional Court, which is expected to decide by next spring whether to reinstate her or formally remove her from office. If the court removes her, a new president will be elected in 60 days.

Nearly half of the 128 lawmakers in Ms. Park’s party voted for impeachment. On Tuesday, 29 of them left the party, Saenuri, to form a new one in preparation for the next presidential election.

Critics of her textbook proposal accused Ms. Park of returning the nation’s history education to the days of her father, the dictator Park Chung-hee, whose government issued textbooks that justified his rule. Even many of Ms. Park’s conservative supporters opposed the plan, despite being critical of many of the privately published history textbooks.

Some of those books discuss sensitive topics like the mass killings of civilians in South Korea during the Korean War, the persecution of dissidents under dictators like her father and his history of collaboration with the Japanese colonial government that ruled Korea before the end of World War II. Many conservative critics have said that such “masochistic historical views” should be kept out of classrooms.

Ms. Park’s government said last year that the private textbooks were ideologically biased and that the new ones would make students proud of their history. When drafts of the state textbooks were unveiled a month ago, opposition parties accused them of highlighting the achievements of Ms. Park’s father, like rapid economic growth during his rule, while giving cursory treatment to abuses like the torture and execution of dissidents. Many local education offices vowed not to endorse the new textbooks.