The frontrunner in South Korea's presidential race has avoided what many political analysts describe as his only serious obstacle to victory. Prosecutors have cleared former Seoul Mayor Lee Myung-bak of fraud accusations, putting him in a position to consolidate a double-digit poll lead over rivals. As VOA's Kurt Achin reports from the South Korean capital, Lee's opponents are not accepting the announcement passively.

Senior prosecutor Kim Hong-il says his office will not prosecute presidential candidate Lee Myung-bak, after an investigation into allegations of stock price manipulation and fraud.

He says investigators found "no evidence" Lee was involved in rigging share prices. Therefore, he says, there will be no prosecution.

Lee, a former Seoul mayor, had been suspected of making tens of millions of dollars using fraudulent financial practices in partnership with Korean-American executive Kim Kyung-jun. Kim, who was arrested in the United States in 2005, was extradited to South Korea last month, fueling speculation Lee would be implicated.

Despite the allegations, Lee has enjoyed a significant lead in public opinion polls as the presidential candidate of the conservative Grand National Party, or GNP. The election will be December 19.

Experts say the fraud allegations were a key factor in the decision last month by fellow conservative Lee Hoi-chang to announce an independent candidacy last month.

Liberal candidates such as former Unification Minister Chung Dong-young had highlighted the stock manipulation allegations, in hope of boosting their campaigns.

Following the prosecutor's announcement Wednesday, GNP Chairman Kang Jae-suk, rebuked Lee's opponents.

Kang says Chung and his party should "kneel down and apologize" for deceiving the electorate.

Chung, however, is not kneeling down. He led a rally Wednesday to protest the decision, and says his campaign will hold more such rallies in the days ahead.

Chung tells a crowd of supporters the prosecution has failed in its duty to reveal the truth - so they must themselves insist that the truth come out.

Kim Jin-hah, a political science professor at South Korea's Keimyoung University, says Lee Myung-bak's opponents have essentially run out of strategic options.

He says there is not really anything opposing candidates can do to dent Lee's polling lead, with so little time before the election.

Latest figures indicate Lee's approval rating hovers at about 40 percent - about 20 percentage points higher than his closest rival.

The constitution bars the current president, Roh Moo-hyun, from running for re-election.