Khan also vetoed several opposition-led bills, including one that proposed a special investigation into Yun’s short-lived declaration of martial law.
The impeachment motion is expected to come up for a vote in the next 24 to 72 hours.
For it to pass, 151 out of 300 deputies must vote for it.
Currently, DP holds 170 out of 300 seats in the parliament. The opposition bloc together has 192 seats.
Opposition parties had hoped that Khan would not interfere with them while serving as the country’s interim president and that he would allow the bills to pass.
But instead, he held firm, deepening the political struggle.
On Tuesday, Han ended a cabinet meeting without considering two opposition-sponsored bills that would have called for a special prosecutor’s investigation into the martial law declaration and corruption allegations involving first lady Kim Keon-hee.
He said he did not put them on the agenda to give the ruling and opposition parties more time to reach a compromise.
But DP leader Park Chang-dae accused him of “buying time and prolonging the rebellion.”
“We have clearly warned that it is entirely up to Prime Minister Han Dak-soo whether he goes down in history as a disgraced figure, as a puppet of rebellion leader Yoon Suk-yeol or a civil servant who dutifully obeyed the orders of the public,” Park said on televised meeting of the party.
And on Thursday, Khan said he would not appoint three judges nominated by the opposition-dominated National Assembly to the constitutional court ruling on Yun’s impeachment unless the rival parties reach a consensus.
To this, Park said that “it has become clear that Han Dak-soo has neither the qualifications nor the desire to defend the constitution,” adding that the opposition would “immediately” introduce a bill of impeachment.
Khan’s ruling People’s Power Party said the opposition’s threats were preventing Khan from “legitimately exercising power”, while a senior official in the prime minister’s office criticized the threats as “very unfortunate”.
Khan took over as interim president after Yoon was ousted earlier this month. If lawmakers vote to impeach Khan, Finance Minister Choi Sang Mok will be next in line.
This latest development in the country’s political turmoil comes as Seoul’s Constitutional Court debates whether to permanently remove Yoon from office.
The court is expected to hold its first public hearing later this week.
It is unclear whether Yoon himself will speak during the hearing, but protesters have vowed to continue their calls for Yoon’s removal during the court proceedings.
Yoon is also under investigation for sedition for his failed attempt to impose martial law in the country.
He refused to accept several subpoenas served to him, and investigators warned they could issue an arrest warrant if he continued to not respond.
Several high-ranking officials, including former defense minister Kim Yong-hyun, former interior minister Lee Sang-min and army chief Park Ahn-soo, are also under investigation.
Additional reporting by Jake Kwon and Hosu Lee in Seoul
