The main opposition Democratic United Party said Friday it will select five finalists for its presidential primary by late this month in an effort to increase competitiveness of its candidates.

Less popular candidates will be cut through public polls among party members and ordinary citizens from July 29-30 before the party kicks off the main primary, its presidential election preparation committee said.

The final presidential candidate will be decided in late September, party officials said.

So far, five candidates from the DUP have announced their bids to run for the December 19 election, but more are expected to do so, including South Gyeongsang Province Governor Kim Doo-gwan.

Another potential opposition candidate is Ahn Cheol-soo, a popular software entrepreneur and professor, but he has not yet made clear his political ambitions despite high approval ratings as a potential candidate.

Even though the political novice has remained vague about his political plans, political parties and experts are paying close attention to whether Ahn, if he decides to run, would join the DUP so there could be a single opposition candidate or run for the top office without party affiliation.

Since the founder of the nation's largest anti-virus software firm made remarks critical of the Lee Myung-bak administration and the nation's large conglomerates last year, he has been considered as liberal and offered to join the liberal party's primary for the top office.

Recent polls showed that Ahn was slightly behind the conservative front-runner Park Geun-hye of the ruling Saenuri Party, garnering more support than heavyweight liberal politicians of the DUP.

Rep. Moon Jae-in, the former aide to late President Roh Moo-hyun, has emerged as one of the strong presidential hopefuls in the liberal camp, but his support still lags behind Ahn and Park. (Yonhap)