SEOUL -- Choi Sang-mok, South Korea's minister of economy and finance who doubles as deputy prime minister for economic affairs, offered to resign Thursday night ahead of a parliamentary vote on a motion to impeach him.

The finance ministry said in a short message that Choi offered to step down at 10:28 p.m. local time (1328 GMT).

Choi offered his resignation just ahead of the vote in the National Assembly's plenary session on the impeachment motion against him that was submitted by the majority liberal Democratic Party on March 21.

The motion was referred to the National Assembly's legislation and judiciary committee for hearings in early April, before it was reported to the parliamentary plenary session Thursday night.

The vote on Choi's impeachment motion was stopped as he offered to step down.

Choi was scheduled to serve as acting president from midnight after former Prime Minister Han Duck-soo, who had been an acting president, announced his resignation earlier in the day amid growing expectations for his presidential run.

Han was widely forecast to announce his bid for the June 3 presidential election on Friday.

Former conservative President Yoon Suk-yeol was impeached last December and removed from office in April over his botched martial law imposition.

With Choi's resignation, Lee Ju-ho, education minister who doubles as deputy prime minister for social affairs, will serve as acting president beginning midnight.