Moon Jae-in, a senior advisor to the main opposition Democratic United Party, said Wednesday that he will decide as quickly as possible whether to make a bid for the presidency.

“The time has come for me to decide what I should do to help realize a regime change,” he said on a radio program.

A former chief of staff to late President Roh Moo-hyun, Moon is considered one of the most viable candidates of the liberal opposition for the next presidency.

The election to pick the successor to conservative President Lee Myung-bak is in December. Lee is barred by law from seeking re-election.

Earlier this month, Moon said that he didn’t enter politics just to become a parliamentarian. It was taken by many in politics and the media as a hint at a presidential bid.

In last week’s general election, Moon won a National Assembly seat in the conservative heartland of Busan. But his efforts to get as many as five other DUP candidates elected in the southern city failed. Only one other liberal candidate won there.

Still, Moon said the Busan electorate is opening up to the liberals.

“We didn’t win as many seats there as we hoped, but we saw a ray of hope that the voter sentiment is changing.”

Moon’s remarks on a presidential bid came as patience was wearing thin in political circles over Ahn Cheol-soo’s prolonged ambiguity about his presidential ambitions.

Ahn, who appears to be a centrist, leaning more left than right, remained silent on news reports earlier this week that he has decided to run and started recruiting allies for his camp.

Moon said the DUP must join forces with the professor to reclaim power from the Saenuri Party.

“It is natural and necessary that the DUP seeks ways to align itself with Ahn,” he said.

“In any way, shape or form, we should go hand in hand with Ahn and I believe that will happen.”

Polls of potential presidential runners show Park Geun-hye, chief of the ruling Saenuri Party, as the frontrunner, followed by Ahn and Moon.

In hypothetical matchups, however, Ahn beat Park for nine months until last week when the ruling party chief overtook him.

On criticism that the DUP lacks efficient leadership, which resulted in several mishaps during the campaign for the April 11 general election, Moon offered a contrasting view.

DUP chief Han Myeong-sook resigned Sunday over the party’s worse-than-expected performance in the general election. The opposition party, once tipped to win easily, secured 127 of the 300 seats up for grabs, while the Saenuri retained its majority with 152 seats.

“I don’t admire Saenuri’s top-down and disciplined way of decision-making, which centers around chief Park Geun-hye,” Moon said.

“The DUP may look messy and noisy, but there is a vibrant democracy,” he stressed.

By Lee Sun-young (milaya@heraldcorp.com)