SEOUL -- South Korean President Moon Jae-in's ruling Democratic Party won Wednesday's general election, claiming the biggest majority in the National Assembly by any party since the country's transition to democracy in 1987.

The left-leaning DP and its satellite partner, the Together Citizens' Party, won 180 seats in the 300-member National Assembly. The main opposition, the conservative United Future Party, and its satellite Future Korea Party took 103 seats.

The landslide victory for Moon's party is a vindication of his government's response to the coronavirus outbreak. It also paves the way for him to push on with his agenda, which includes "inclusive" income redistribution policies, reform of the prosecution system, and the Korean Peninsula peace process.

"This general election surprised the world again. Thanks to people's cooperation and participation, we became to only major country to host a nationwide election amid the COVID-19 pandemic," Moon said in a statement on Thursday. "[The government] will trust people and move forward bravely, even though we face a unprecedented national crisis. We will overcome it."

Despite the coronavirus outbreak, voters lined up from early morning to cast their ballots on election day. The turnout was 66.2% -- the highest in a general election since 1992 -- with a record 26% of eligible citizens taking part in early voting last week.

Analysts say the government's handling of the coronavirus was a vote winner. South Korea reported 27 new cases on Wednesday, keeping the number under 40 for seven consecutive days. The total number of cases has reached 10,591 with 225 deaths, but the fatality rate of around 2% is one of the lowest in the world.

The country's public health authorities have tested more than half a million people, and locked down cluster infections. The government has encouraged all citizens to remain indoors and has mandated social distancing measures, such as the closing of parks, bars, sporting venues and other public places. Yet it has not resorted to an all-out shutdown of the country.

A Realmeter opinion poll released on Monday showed 54.5% of respondents approving of Moon's performance, up from 48.7% in early March.

"The comparatively high degree of success the government has had in containing the outbreak has significantly boosted Moon's political standing and reduced the risk that disgruntled [DP] supporters and independents will be motivated to vote against his party's candidates in the elections," said Scott Seaman, Asia director at Eurasia Group.

"The proportion of independent and unaffiliated voters ... has declined steadily over the past several weeks, with more people in this segment of the electorate appearing to flow into the [DP] camp as the pace of new cases slackened and the government received more recognition for its efforts."

The Democrats performed well in some key races.

Former Prime Minister Lee Nak-yon beat UFP leader Hwang Kyo-ahn in a Seoul constituency, raising his odds of running for the presidency in 2022 when Moon's single five-year term expires. Hwang resigned as party chief to take responsibility for the defeat.

"I will put priority on overcoming COVID-19 and the economic setback as commanded by the people," Lee said on Thursday after winning the election. "People gave a lot of seats to the Democratic Party and the Together Citizens' Party, putting huge responsibility on us."

Moon's former spokesperson Ko Min-jung defeated ex-Seoul Mayor Oh Se-hoon of the UFP.

In one piece of good news for the UFP, Thae Yong-ho became the first North Korean defector to win a seat in the parliament through an election.

The DP thrived in many regions, including Seoul, Gyeonggi Province and Gwangju, while the UFP won seats in Busan, Daegu, and North and South Gyeongsang provinces.

The two main parties launched their own satellite parties in an attempt to win more seats in the proportional vote. The left-wing Justice Party came third with six seats.