Malaysian Prime Minister Mahathir Mohamad tendered his resignation to the king Monday, his office said in a statement, but did not give further details.
Mahathir's resignation followed talks over the weekend between some members of his party and opposition groups on forming a new government to prevent the transition of power to his hand-picked successor Anwar Ibrahim.
Mahathir, 94, the world's oldest prime minister, and Anwar 72, joined forces in 2018 to win the election and oust the ruling alliance at that time, on the condition that Mahathir would cede power to Anwar.
It was not immediately clear what step Malaysian King Sultan Abdullah Sultan Ahmad Shah would take under the circumstances.
According to analysts, the king could decide if any political group has a parliamentary majority, otherwise the king may dissolve the parliament for snap elections.
Anwar's wife Wan Azizah Ismail is the deputy prime minister of Malaysia and would become the highest government official if Mahathir's resignation were accepted.
