South Korea’s ruling party has thrown its support behind attempts to impeach embattled President Yoon Suk Yeol over his ill-fated decision to declare martial law that sparked a political crisis and widespread public anger in the country.

The announcement came moments before Yoon delivered a defiant speech on Thursday in which he justified his hugely controversial martial law decision, rejecting growing calls from across the political spectrum for him to stand down.

The People Power Party (PPP) had initially refused to back impeachment, hoping instead Yoon would resign from office.

But its leadership said attempts to persuade Yoon had made no progress.

“We tried to find a better way than impeachment, but that other way is invalid,” party leader Han Dong-hoon said. “Suspending the president from his duties through impeachment is the only way for now, to defend democracy and the republic.”

The main opposition Democratic Party is preparing a new impeachment motion against Yoon, with a vote expected as soon as Saturday.

Last weekend, Yoon survived an impeachment vote after members of the PPP left parliament and boycotted the vote.

The PPP’s reversal dramatically increases the pressure on Yoon and the likelihood that the next impeachment attempt will be successful.

Han said party lawmakers were free to vote according to their “belief and conscience” at the next vote.

“I believe our party members will vote for the country and the people,” he said.

The PPP’s announcement is the latest dramatic turn in what has become a stunning political showdown in South Korea over the past week.

The president’s shocking but short-lived declaration of martial law in a late-night address on December 3 quickly backfired and galvanized many in the vibrant democracy to call for his removal.

Dramatic scenes from that night showed security forces breaking through windows in the National Assembly to try and prevent lawmakers from gathering, and protesters confronting riot police.

Within just six hours, the leader was forced to back down, after lawmakers forced their way past soldiers into parliament to strike down the decree.

In the days since, Yoon has faced intense pressure to stand down, with protesters and opposition figures demanding his impeachment – and support wavering even within his own party and the military.

But he has remained defiant.

“I will fight until the last moment with the people,” Yoon said in Thursday’s speech.

“I apologize again to the people who might have been surprised and nervous due to the short-lived martial law. Please trust in my passionate loyalty for you, the people.”