Not many election issues are more crucial than whether to rewrite the Constitution. Yet it is Moon Jae-in of the main opposition Democratic United Party alone that has committed himself to pursuing Constitutional revision as a presidential candidate.

True, Park Geun-hye of the ruling Saenuri Party says she will consider a constitutional revision if she is elected president. But she refuses to commit herself to it, saying that it is not desirable to approach the issue for electioneering purposes or present a set schedule ahead of the election. Nor is the independent Ahn Cheol-soo any more committal. But the electorate apparently wishes to hear them say in unambiguous terms where they stand on the issue.

It is a general agreement in public opinion that the 1987 amendment to the Constitution has outlived its purpose of keeping a president from holding power for too long and, by doing so, preventing him from building a base for authoritarian governance, as Park Chung-hee and Chun Doo-hwan did with support from the military.

Lawmakers share this view. According to a recent survey, 87 percent of the members of the National Assembly support the proposal to rewrite the Constitution. The level of legislative support is reassuringly high, given that an amendment needs approval from two-thirds or more of the members if it is to be put to a referendum.

In 1987, a constitutional amendment was made possible because the Chun administration surrendered to anti-government activists and students, who fought fiercely for the restoration of democracy in the nation. Foremost among the changes was the shift from the single, seven-year presidency to the election of the president by direct, popular vote for a single, five-year term in office.

During the past 25 years, democracy in Korea has undoubtedly matured so much that another military-backed dictatorship is not easily conceivable. Now it is the general consensus that the Constitution needs to be amended in favor of greater accountability and more decentralization in governance.

Indeed, a president permitted one single term tends to pay less attention to his scorecard than one planning to seek reelection. Worse still, so much power is held in the hands of the president that it is often called an imperial presidency.

An alternative is to elect a president to a four-year term, permit him to seek a second four-year term and make him share power with the vice president or the prime minister. Another proposal is a shift to the cabinet system of governance, which its advocates say will enhance accountability and decentralization at the same time.

President Lee Myung-bak and his two immediate predecessors, Kim Dae-jung and Roh Moo-hyun, found that the 1987 amendment was flawed when accountability and decentralization were considered. During their presidential campaigns, each of them promised to seek to revise the Constitution.

But they did not make good on their promises when they were elected president. Instead, talk of constitutional revision was made taboo during the early years of their presidency. That was understandable, given that they were apparently concerned that public debate on a constitutional revision, should it go into full swing, would steal public attention away from their coveted projects when they were launched.

Apparently for the same reason, Park and Ahn are reluctant to commit themselves to constitutional revision even though they support decentralization.

In this regard, it should not come as a surprise if many people wonder aloud if Moon will make good on his promise. Moreover, his sincerity was further called into question when he abandoned his earlier proposal to have the president share much of his power with the prime minister and called for his power sharing with the vice president, whose post would have to be newly created. He offered no explanation for the change.

It would make greater sense to devolve much of the presidential power to the prime minister, with his office set to be relocated to the new administrative town, Sejong City in central South Korea, along with most of the ministries and other government agencies. The presidential office will remain in Seoul.

With only six weeks to go until the election, the three candidates will do well to make a clean breast of it now, and tell the public what they really think about the issue. If they are to pursue a constitutional revision, the timeline is critical. The entire process will have to be completed in the first year of the presidency if it is to keep its momentum rolling.