South Koreans will vote this week in local elections and parliamentary elections amid expectations that the results will boost or weaken the mandate of the new government of President Yoon Suk-yeol.

Up for grabs in Wednesday's elections are 17 metropolitan mayors and provincial governors, 226 lower-level council heads, as well as 779 seats in provincial and metropolitan councils, and 2,602 in lower-level local councils.

Also at stake will be seven National Assembly seats in parliamentary by-elections.

Voting will kick off at 6:00 a.m. and run until 6:00 p.m. Wednesday at 14,465 polling centers nationwide, according to the National Election Commission (NEC).

COVID-19 patients and those in quarantine will be allowed to vote between 6:30 p.m. and 7:30 p.m.

Eligible voters total 44.3 million, but 9.13 million of them already cast their ballots during the two-day early voting last week.

Turnout of the advance voting came to 20.62 percent, the highest for any local elections, the NEC said. It expects final turnout for Wednesday's elections to surpass 60.2 percent logged in the 2018 local elections.

The elections come less than a month after Yoon took office.

Recent polls showed the People Power Party (PPP) taking leads in most big races, except those in the southwestern Honam region, the home turf of the Democratic Party (DP).

The PPP hopes it can extend the momentum of the presidential election victory. It aims to win more than half of 17 gubernatorial and mayor posts.

The conservative party believes Yoon's summit with U.S. President Joe Biden and recent North Korea provocations can be helpful for its campaign, especially among those seeking the stabilized operation of the Yoon administration.

The DP, which controls a majority in the National Assembly, is looking to recover from the March 9 presidential election defeat and expand its power across the nation to keep the Yoon government in check.

The liberal party hopes to repeat the success of the 2018 local elections when it scored a landslide victory.

The DP, however, is worried a recent internal feud, which was sparked by the DP co-interim chief Park Ji-hyun's call for a sweeping reform of the party, and a sexual misconduct case involving one of its lawmakers may undermine its chances in the elections.

Both parties view the capital area, where half of the country's population resides, as a key battleground.

The Seoul mayoral election has been mainly a two-horse race between current Mayor Oh Se-hoon and former DP Chair Song Young-gil. Recent polls showed Oh, who is running for a fourth term on the PPP ticket, leading Song by a wide margin.

The race for Gyeonggi governor has been largely between former lawmaker Kim Eun-hye of the PPP and former Finance Minister Kim Dong-yeon of the DP. Recent polls showed the two were running neck and neck.

When it comes to the parliamentary by-elections, all eyes are on former presidential candidates Lee Jae-myung and Ahn Cheol-soo, since the victory could help them gain ground in their respective parties and pave their ways to have another shot at the presidency.

Ahn, who withdrew from the presidential race to endorse Yoon, is chasing the seat representing the Bundang-A district of Seongnam, just south of Seoul, as the PPP candidate. After the presidential election, Ahn's People's Party merged with Yoon's PPP.

Recent polls showed Ahn leading by a big margin against Kim Byoung-gwan of the DP. Ahn is seeking his first parliamentary membership since 2017.

Lee, who lost to Yoon in the March 9 presidential election only by a razor-thin 0.73 percentage-point gap, is hoping to win the seat in the Gyeyang-B district in Incheon, 40 kilometers west of Seoul, as the DP candidate.

Recent polls showed Lee, former Gyeonggi governor, in a tight race against Yoon Hyung-sun of the PPP. (Yonhap)