Ahn Cheol-soo, a South Korean software mogul who dropped out of last year's presidential race to support an opposition candidate, was to arrive home from a months-long overseas trip later Monday to run for a parliamentary seat in next month's by-election.

Ahn, who founded South Korea's largest anti-virus software firm AhnLab, enjoyed immense popularity among young liberal voters ahead of the December presidential election, posing a serious challenge to the ruling and opposition party contenders.

The 51-year-old entered the presidential campaign amid growing public disenchantment with the political establishment and painted himself as an outsider untainted by party politics who represented the public's desire for change.

Ahn, however, quit the race in November and threw his support behind Moon Jae-in of the main opposition Democratic United Party (DUP) in a bid to consolidate the opposition vote. He left for the United States on the day of the Dec. 19 vote, and ruling party contender Park Geun-hye went on to be elected South Korea's first female president.

Ahn plans to announce his bid for the by-election slated for April 24 once he arrives in Seoul, Rep. Song Ho-chang, an independent lawmaker who bolted from the DUP to co-chair Ahn's presidential campaign, said in a press conference last week.

Ahn will run for a seat in the Nowon district in northern Seoul, which was vacated after a minor progressive party lawmaker last month received a suspended prison sentence from the Supreme Court.

While it had been widely expected Ahn would return to politics, political analysts and the media hold out the possibility he may establish his own party with his supporters.

The former candidate is scheduled to hold a news conference later in the day upon arriving at Incheon International Airport, Seoul's main gateway, where he is expected to outline his political plans.

Before boarding his plane, Ahn told reporters at San Francisco International Airport that he spent the past three months in the U.S. in contemplation, while reading books, thinking and taking frequent walks.

He also said he watched the recent historical drama film "Lincoln," which tells the story of the final four months of the former U.S. president's life.

"It was very moving," he said.

Referring to the film's depiction of Lincoln's efforts to have the 13th amendment to the Constitution passed by the House of Representatives, Ahn said he was moved by how the former president achieved his goal by persuading the ruling and opposition parties, and thinking strategically.

"In the end, politics is about producing results." (Yonhap News)