It is not rare for Korean politicians to break their promises, be they those they made to their fellow politicians or voters. One good example is the promise to amend the Constitution by June this year.

The proposal, once upheld by all major parties and senior politicians, has effectively fallen apart as the National Assembly failed to revise the Referendum Act by Monday.

A referendum is necessary for approving a constitutional revision bill, and President Moon Jae-in and his ruling Democratic Party of Korea wanted to put Moon’s bill to a plebiscite on the day of the June 13 local election.

But the current Referendum Act was ruled unconstitutional in 2014 for its exclusion of overseas Koreans as eligible voters. Without addressing the problem, there could be no referendum and due to the minimum number of days needed for preparing the plebiscite, the National Assembly had to revise the act by Monday.

All major political groups, including President Moon and the ruling and opposition parties, should share the blame for failing to keep their promise to put a constitutional revision bill to a national referendum alongside the June 13 election.

There had been persistent political and public calls for the revision of the current Constitution, a product of the 1987 pro-democracy movement that restored election of the president in a direct popular vote and limited the president to a five-year single term. The main reason was that the basic law was focused on ending the successive military dictatorships and that they do not reflect the changes Korean society went through over the three decades.

The ouster of former President Park Geun-hye for corruption and abuse of power further heightened the call as many saw concentration of power in the president as a main cause of the problems with the Korean presidency.

Riding such a public sentiment, all contenders in the presidential by-election, including Moon and Hong Joon-pyo of the main opposition Liberty Korea Party, pledged to revise the supreme law alongside the June 13 local election.

In line with the consensus, the rival parties launched a special parliamentary committee in late 2016, but they made little progress due to political bickering. Hong and his Liberty Korea Party bear the biggest share of the blame for the lack of progress as they changed their mind and opposed an early revision. They cited the presumption that holding a national referendum and the local election simultaneously may work against the conservative party.

Moon was also ill-advised as he -- instead of persuading the opposition -- invoked the presidential right to propose a constitutional revision bill.

His unilateral move raised questions about his motives, since the ruling party does not have enough parliamentary seats to pass the amendment bill alone. That raised suspicions that he simply wanted to make the opposition a scapegoat.

Moreover, Moon’s bill encountered stiff objection from the opposition because it included few measures to curb the power of the president, except for reducing the time in office to four years and allowing a second term. For instance, the Liberty Korea Party insists that the prime minister should not be appointed by the president, but by the National Assembly.

This and other wide gaps between the rival parties are unlikely to be narrowed anytime soon. Besides, the parties are now locked in severe political wrangling over an online opinion rigging scandal and other contentious issues. The inter-Korean summit, which will be followed by a meeting between US President Donald Trump and North Korean leader Kim Jong-un, will also weigh heavily on domestic politics.

It means that for more time to come, we may have to continue to see only the blame game between the rival parties with no early revision of the outdated supreme law in near sight.