Rep. Ahn Cheol-soo of the ruling People Power Party attends a party meeting at the National Assembly in Seoul, April 15. Yonhap

Presidential hopefuls face a growing dilemma about if and when to return to President Yoon Suk Yeol's side as he currently faces a huge political setback after the ruling party's defeat in the general elections on April 10.

Yoon appears as a lonely figure these days as he is on the verge of becoming the first president since Korea's democratization in 1987 to work with an opposition-controlled Assembly for all five years of his term.

Rep. Ahn Cheol-soo of the ruling People Power Party (PPP) is looking to distinguish himself from Yoon by expressing his frustration with the presidential office for the party's crushing election defeat. The PPP and its satellite party collectively won 108 seats in the 300-member National Assembly, while the main opposition Democratic Party of Korea (DPK) and its satellite party secured 175 seats.

"The election defeat was due to government failure. If the government and ruling party reject change and believe ‘we lost, but we fought well,' they will face bigger failures," he wrote on Facebook, Sunday.

"I urge the key officials responsible for the electoral defeat to step down and take time to reflect, innovate and reconstruct rather than looking for scapegoats."

Ahn, a former presidential election coalition partner of Yoon, expressed his intent to vote for a special probe bill pushed by the DPK to investigate allegations that the presidential office and the Ministry of National Defense inappropriately interfered in a military investigation into a young Marine's death last year.

The bill has been pending in the Assembly since early this month, after the DPK unilaterally designated it as a fast-track bill with expedited deliberations.

The doctor-turned-politician also criticized Yoon for failing to compromise on its plan to increase the number of medical school seats by 2,000 next year amid a prolonged walkout by more than 90 percent of the country's 13,000 trainee doctors.

Han Dong-hoon, the ruling People Power Party's former interim leader, delivers a statement after the party's defeat in the April 10 general elections during a press conference at PPP headquarters in Seoul, April 11. Joint Press Corps

Han Dong-hoon, former interim leader of the PPP who is also known as Yoon's close aide from their days as prosecutors, has been keeping his distance from Yoon after the party's election defeat in an apparent move to step out of Yoon's shadow and find a path to a future in politics.

Han rejected the beleaguered president's invitation to a luncheon with PPP emergency committee members citing ill health. The rejection came amid PPP members' ongoing arguments over who is responsible for the election defeat and who will take the helm of the party to restore the public's trust.

Meanwhile, Daegu Mayor Hong Joon-pyo, who has railed against Han, blaming his campaign strategy for the party's defeat, has been showing support for Yoon lately. Hong and Yoon had dinner together on April 16 to discuss post-election political strategies.

"If a planet deviates from its star without knowing its subject, it becomes a lost child in space," Hong wrote on Facebook, Saturday. Hong also wrote that Han "acted as if he were the heir-apparent of Yoon" but "was abandoned after arrogantly challenging his master."

Seoul Mayor Oh Se-hoon, another potential candidate for the next presidential election, has been expanding his scope of leadership. Oh met with both elected lawmakers and unsuccessful candidates of the PPP before Yoon met with them. He plans to meet with successful candidates of the DPK representing constituencies of the capital on Tuesday in an apparent move to showcase his political tolerance.