SEOUL, South Korea (AFP) — South Korean President Yoon Suk Yeol was still clinging to power Thursday, with his party announcing they will oppose an impeachment motion after his short-lived imposition of martial law stunned the world.

Yoon suspended civilian rule late Tuesday and deployed troops and helicopters to parliament only for lawmakers to vote down the measure and force him into a U-turn in a night of protests and drama.

Seoul’s allies were alarmed — Washington said it found out via television — and the opposition quickly filed an impeachment motion saying Yoon “gravely violated the constitution and the law.” A vote is set for Saturday at around 7 p.m.

South Korean police also announced Thursday they were investigating Yoon for “insurrection” — a crime that transcends presidential immunity and can carry the death penalty — after the opposition filed a complaint against him and other key figures involved.

The opposition holds a large majority in the 300-member legislature and require only a handful of defections from Yoon’s People Power Party (PPP) to secure the two-thirds majority needed for impeachment.

But on Thursday, PPP leader Han Dong-hoon said that while he had demanded Yoon leave the party over his “unconstitutional martial law,” he would block the impeachment motion.

“All 108 lawmakers of the People Power Party will stay united to reject the president’s impeachment,” party floor leader Choo Kyung-ho said.

According to a new poll issued Thursday by Realmeter, 73.6 percent of respondents supported the impeachment. More protests were expected later Thursday.

If the motion passes, Yoon will be suspended pending a verdict by the Constitutional Court. If the judges give the nod, Yoon will be impeached and new elections must take place within 60 days.