A win for conservative Park Geun-hye would see her return to the presidential palace where she served as her father's first lady in the 1970s after her mother was assassinated.
Seoul, South Korea
The daughter of a former military ruler led the count of votes in South Korea's presidential election on Wednesday, putting her on track to become its first woman head of state although her narrow advantage meant the race was set to go to the wire.
A win for conservative Park Geun-hye would see her return to the presidential palace where she served as her father's first lady in the 1970s after Ms. Park's mother was assassinated by a North Korean-backed gunman.
With a third of the votes counted, Park led by 53 percent to 47 percent for her left-wing challenger, human rights lawyer Moon Jae-in, and broadcaster KBS said based on that, she would win by at least four percentage points.
She also led an exit poll by 50.1 percent to Moon's 48.9 percent.
Final turnout was 75.8 percent, just less than the 77 percent her opponent had appealed for in a bid to turn out the youth vote that was more likely to be for him.
If she does win, Park will take office for a mandatory single, five-year term in February and will face an immediate challenge from a hostile North Korea and have to deal with an economy in which annual growth rates have fallen to about 2 percent from an average of 5.5 percent in the past 50 years.
She is unmarried and has no children, saying that her life will be devoted to her country.
At the headquarters of her Saenuri party, officials greeted the exit polls with a huge cheer, although a clear picture of results may not emerge until 11 p.m. (1400 GMT).
"I'm sure it will go well," said Kim Sung-joo, co-chairwoman of Park's election committee.
The legacy of her father, Park Chung-hee, who ruled for 18 years and transformed the country from the ruins of the 1950-53 Korean War into an industrial power-house still divides Koreans.
For many conservatives, he is South Korea's greatest president and the election of his daughter would vindicate his rule. His opponents dub him a "dictator" who trampled on human rights and stifled dissent.
"I trust her. She will save our country," said Park Hye-sook, who voted in an affluent Seoul district, earlier in the day.
"Her father ... rescued the country," said the housewife and grandmother, who is no relation to the candidate.
For younger people, the main concern of the election is the economy and the creation of well-paid jobs in a country where income inequalities have grown in recent years.
Cho Hae-ran, who is married and works at a trading company, believed Moon would raise wages if he won.
"Now a McDonald's hamburger is over 5,000 Korean won ($4.66) so you can't buy a McDonald's burger with your hourly pay. Life is hard already for our two-member family but if there were kids, it would be much tougher."
Park has spent 15 years in politics as a leading legislator in the ruling Saenuri party, although her policies are sketchy.
Park has a "Happiness Promotion Committee" and her campaign was launched as a "National Happiness Campaign," a slogan she has since changed to "A Prepared Woman President."
She has cited former British Prime Minister Margaret Thatcher, a tough proponent of free markets, as her role model as well as Angela Merkel, the conservative German Chancellor who is Europe's most powerful leader.
One of those who voted on Wednesday was Shin Dong-hyuk, a defector from North Korea who is the only person known to have escaped from a slave labour camp there.
He Tweeted that he was voting "for the first time in my life", although he didn't say for whom.
Park has said she would negotiate with Kim Jong-un, the youthful leader of North Korea who recently celebrated a year in office, but wants the South's isolated and impoverished neighbour to give up its nuclear weapons programme as a precondition for aid, something Pyongyang has refused to do.
The two Koreas remain technically at war after an armistice ended their conflict. Kim Il Sung, the grandfather of the North's current leader, ordered several assassination attempts on Park's father, one of which resulted in her mother being shot to death in 1974.
Park herself met Kim Jong-un's father, the late leader Kim Jong-il, and declared he was "comfortable to talk to" and he seemed to be someone "who would keep his word".
The North successfully launched a long-range rocket last week in what critics said was a test of technology for an intercontinental ballistic missile and has recently stepped up its attacks on Park, describing her as holding a "grudge" and seeking "confrontation", code for war.
Park remains a firm supporter of a trade pact with the United States that and looks set to continue the free-market policies of her predecessor, although she has said she would seek to spread wealth more evenly.
Moon had pledged to tackle the power of the country's vast export-oriented industrial conglomerates, the so-called chaebol, but Park has stressed their value in creating jobs.
The biggest of all the chaebol, Samsung Group, which produces the world's top selling smartphone as well as televisions, computer chips and ships, has sales equivalent to about a fifth of South Korea's national output.