Supporters of Democratic presidential nominee Vice President Kamala Harris look at the first results, during the US election night party, in Geneva, Switzerland, Tuesday. (EPA-Yonhap)

Democratic presidential candidate Kamala Harris and her Republican rival Donald Trump secured anticipated wins in states favoring their respective parties on Tuesday, as political attention gravitates to key battleground states that will likely decide the outcome of this year's general election.

With vote counting under way, Harris won New Jersey, New York, Illinois, Delaware and other Democratic-leaning states, while Trump clinched victories in Florida, Alabama, Mississippi, Texas, Ohio and other reliable states, the Associated Press projected.

Polls closed in the seven swing states -- Pennsylvania, Michigan, Wisconsin, Georgia, Arizona, Nevada and North Carolina -- but it is too early to call them.

The Keystone State with 19 electoral votes -- the highest among the swing states -- is seen as a must-win prize for both candidates. With 51 percent of the vote counted, Trump leads Harris in Pennsylvania 50.6 percent to 48.5 percent as of 10:16 p.m., EST, according to AP.

To occupy the Oval Office, a candidate must win at least 270 electoral votes out of the total 538 electors representing the 50 states and the District of Columbia.

American voters cast ballots to pick a new president who will steer the United States through a litany of nettlesome issues, including deep national division, still-high prices and global security challenges, like North Korea's nuclear adventurism and Russia's war in Ukraine.

The high-stakes Election Day capped an extremely close and eventful race between Harris, 60, and Trump, 78 -- two sharply contrasting candidates in terms of age, gender, race, political inclinations and policy orientation.

According to the Bipartisan Policy Center, roughly 244 million Americans are eligible to vote in 2024. If voter turnout is as high as that of the 2020 election at 66.6 percent, more than 162 million were expected to cast ballots in this election cycle.

More than 85.9 million Americans have already cast an early ballot, data from the University of Florida's Election Lab showed.

After voting in Florida, Trump voiced confidence over his electoral chances, claiming that he will have a "very big victory." He also cast this year's campaign as the "best" of the three campaigns that he ran.

"I felt very confident ... We went in with a very big lead today and it looks like Republicans have shown up in force," he told reporters with his wife, Melania Trump, standing by his side.

Regarding a question about whether he would concede should he lose in the presidential vote, he said he would be the "first" to acknowledge it if it is a "fair" election.

"So far, I think it's been fair. I think there's been a lot of court cases," he said. "Part of that is because we have too complicated a process."

Later in a social media post, Trump said that there is "a lot of talk about massive cheating in Philadelphia" -- remarks that added to concerns that he might not concede defeat if he loses. In the 2020 election, he claimed to have won the presidency when Pennsylvania was called in favor of President Joe Biden.

Appearing on a Pittsburgh-based radio show, Harris also called on people to get out and vote.

"I would urge everyone to just remember that in our democracy, the people get to decide, and your vote is your power," she was quoted by CNN as saying.

Harris attended an election night watch party at her alma mater, Howard University in Washington, a historically Black university. Trump watched election results in Palm Beach, Florida.

The Democratic standard-bearer's vice presidential running mate is Minnesota Gov. Tim Walz, while Trump's running mate is Ohio Sen. J.D. Vance.

South Korea has been carefully watching developments in the US election as a new occupant of the White House could bring a shift in America's foreign policy that affects the Seoul-Washington alliance as well as the way Washington handles Pyongyang's evolving nuclear and missile threats.

Having underlined the importance of America's leadership on the global stage, Harris, if elected, is expected to build on key tenets of President Joe Biden's foreign policy, including cementing a network of US allies and partners to confront shared security challenges.

Should Trump return to office, he could highlight his "America First" credo that is expected to put pressure on allies and partners to take greater responsibilities for their own security and curtail America's costly involvement overseas.

Seoul's foreign ministry said that South Korea will continue to maintain close cooperation with a new US administration, as it highlighted "strong bipartisan support" for the bilateral alliance in Washington.

This year's election cycle has been marked by a spate of unprecedented events, including two assassination attempts against Trump, Biden's surprise exit from the White House race, and Trump's conviction in a hush-money trial and other legal woes.

It remains uncertain when the winner will be named. In the 2020 election that proceeded amid COVID-19, the race was called for Biden four days after the vote. But the 2016 election was called for Trump in the wee hours of the morning after Election Day.

Should Harris be elected, she would make history by becoming the first female, first Asian American and first Black woman to occupy the Oval Office. Should Trump prevail, he would be the second president to serve non-consecutive terms after Grover Cleveland in the late 1800s.

Observers said that given the dead heat between the two candidates, more time could be needed to get the election outcome. A razor-thin margin in a battleground state could trigger a recount of votes, and any missteps at polling stations or other unforeseen mishaps could delay the counting process.

The victor of this year's presidential race is to take office Jan. 20.

Also up for grabs in Tuesday's election are 34 Senate seats and all 435 House seats.

Currently, Democrats hold a slight majority in the Senate, controlling 51 seats with the help of three independents that caucus with the Democrats, while Republicans hold 49 seats. In the House, Republicans have a slim majority with 220 seats to Democrats' 212.

Among Korean American politicians, Rep. Andy Kim won a Senate seat for New Jersey, making history as the first Korean American elected to the upper house of Congress.

There are also three Korean American congresswomen seeking a third-term in the House of Representatives. They are Reps. Young Kim (R-CA), Michelle Park Steel (R-CA) and Marilyn Strickland (D-WA). Aside from the current lawmakers, Dave Min, a Korean American Democrat, is bidding to join the House. (Yonhap)