[LEAD]
South Korea has a new president. Democratic Party presidential candidate Lee Jae-myung has been elected the 21st president of South Korea.
With a final margin of about 2.89 million votes, he secured the most ballots received in a Korean presidential election to date. His term began at 6:21 a.m. on Wednesday.
[REPORT]
At 2:30 a.m. Wednesday, six hours after ballot counting began...
KBS's election prediction system Decision K+ confirmed that Democratic Party presidential candidate Lee Jae-myung had been elected 21st president.
The government has been switched after three years.
Lee won more than 17.28 million, or 49.42%, of the votes, beating People Power Party presidential candidate Kim Moon-soo.
That's the most ballots received in a Korean presidential election to date.
The gap between Lee and Kim is some 2.89 million votes, or 8.27%p.
He received overwhelming support in the Honam region and beat Kim in Seoul and the Chungcheong region, where he lost in the presidential race three years ago.
However, he was outperformed by Kim in the conservative Yeongnam and Gangwon regions.
The results of exit polls show that Lee beat Kim in all age groups except for voters in their 60s, 70s and above.
Lee received particularly strong support from voters in their 40s and 50s.
President Lee Jae-myung stepped out of his residence shortly after his victory became clear.
Lee Jae-myung / President
I respect the people's great decision. I will do my best to fulfill this enormous
responsibility and mission to live up to the people's expectations.
Lee's presidential term began at 6:21 a.m. on Wednesday after the National Election Commission confirmed his election.