SEOUL, South Korea (AP) — South Korea’s prime minister and senior presidential officials offered to resign en masse on Thursday, media reports said, after their conservative ruling party suffered a crushing defeat in parliamentary elections.

The results of Wednesday's election posed a huge political blow to President Yoon Suk Yeol, setting back his domestic agenda and leave him facing an intensifying political offensive by his liberal opponents during his remaining three years in office.

Prime Minster Han Duck-soo and top advisers to Yoon submitted their resignations, South Korean media including Yonhap news agency reported. Yoon's office didn't immediately officially confirm the reports.

In a a separate news conference, ruling People Power Party leader Han Dong-hoon said he would step down as well to take responsibility for the election defeat.

With most of the votes counted, the main opposition Democratic Party and its satellite party appear to have won a combined 175 seats in the 300-member National Assembly. Another small liberal opposition party was expected to win 12 seats under a proportional representation system, according to South Korean media tallies.

Yoon’s ruling People Power Party and its satellite party were projected to have obtained 109 seats.

The final official results were expected later Thursday.

But the outcome means the liberal opposition forces would extend their control of the parliament, though they will likely fail to garner the super majority of 200 seats that gives them legislative powers to overturn vetoes and even impeach the president.

Wednesday’s election was widely seen as a midterm confidence vote on Yoon, a former top prosecutor who took office in 2022 for a single five-year term.

He has pushed hard to boost cooperation with the U.S. and Japan as a way to address a mix of tough security and economic challenges. But Yoon has been grappling with low approval ratings at home and a liberal opposition-controlled parliament that has limited his major policy platforms.