June 1 (UPI) — Ahead of South Korea’s snap presidential elections on Tuesday, the nation’s diplomatic relations with North Korea and China have risen to the fore — and officials are investigating voting irregularities.

“The relations between South Korea and China have become the worst ever,” Lee Jae-myung, the left-leaning presidential candidate leading public opinion polls, said in remarks to The New York Times. “I will stabilize and manage the relations.”

The already historically low diplomatic relations between South Korea and North Korea, as well as its relations with China, further soured after then-South Korean President Yoon Suk-yeol was removed from office over imposing martial law in April, a move that was short-lived.

The bellicose North Korea has distance itself from South Korea following the failed 2019 Hanoi summit between Korean Korean Kim Jong-un and President Donald Trump, which continued during Yoon’s conservative administration.

Pyongyang last year ended its founding goal of reunification and named South Korea its “principal enemy.”

The Yoon administration also shook a delicate diplomatic balance between Washington and Beijing. China was South Korea’s biggest post-Cold War trading partner, but the United States was its main military ally.

Early voter turnout was strong, but poll watchers expressed concern over irregularities. In past elections, the National Election Commission dismissed the irregularities as “simple mistakes” or “minor mistakes.”

The NEC has pushed back on claims of polling irregularities.

Independent candidate Hwang Kyo-ahn withdrew from the race Sunday, saying he was shifting his efforts to supporting People Power Party’s Kim Moon-soo.

South Korean independent presidential candidate Hwang Kyo-ahn said on Sunday that he is withdrawing from the race to support People Power Party’s Kim Moon-soo, local media reported.

“I will withdraw my efforts to supporting Kim Moon-soo to protect the government,” he said. My final task is to prevent election fraud. Fortunately, Kim has pledged to address election irregularities.”

Polling places are scheduled to receive ballots from 6 a.m. to 8 p.m. Tuesday, which is a holiday because of the election.

“We are at a critical juncture,” Lee said on social media Sunday, “and it is in the hands of each and every one of you that we can return this country to its people, halt the retreat of democracy, and create a truly great Korea.