A former opposition leader announced Thursday he will run for president, saying he would be a dependable leader who cares deeply about the working class and could hold an increasingly divided society close together.

Sohn Hak-kyu, a special advisor for the main opposition Democratic United Party, is one of the leading opposition hopefuls for the December election, along with Rep. Moon Jae-in, South Gyeongsang Province Gov. Kim Doo-gwan and popular software developer and scholar Ahn Cheol-soo.

"The mission of the times the next president must realize with the highest priority is nothing other than (improving) livelihoods and social unity," Sohn said during a press conference at a plaza in central Seoul, speaking to about 100 supporters.

Sohn, who served as chief of the DUP in 2010-2011, said he would be a president who "looks after the livelihoods of ordinary people with a humble attitude, connects more closely with the people, revitalizes small- and medium enterprises" and promotes social unity.

Sohn called for a change in government, claiming democracy has been trampled on and power abused under the administration of President Lee Myung-bak over the past five years.

"How can we put the fate of the Republic of Korea in the hands of outdated forces?" he said.

Sohn pledged to raise the country's employment rate to 70 percent by 2020 and take a series of other reform measures to end discrimination against irregular workers, make corporate governance more transparent and taxation more fair, and introduce a ceiling on medical treatment costs. (Yonhap)