The agreement came in a meeting between Lee Han-koo, floor leader of the ruling Saenuri Party, and Park Ki-choon, his counterpart of the main opposition Democratic United Party (DUP), at the National Assembly, officials of the two parties said.
Both parties pledged to push for a constitutional revision that would reduce the president's power before the presidential election in December last year.
There have long been calls for constitution change to curtail the president's "too much power."
In South Korea, irregularities involving those close to the president have plagued almost all governments. Many attribute the outbreak of many scandals implicating those in power to the country's "emperor-like" presidency.
During her campaign, President Park Geun-hye promised to seek constitutional amendments to improve the people's basic rights and allow a president to serve two four-year terms, if she wins the election.
Critics say the current five-year, single-term system makes a president an early lame duck, and self-righteous and stubborn.
The issue has been a major source of discussion in the country for years.
reporter
Park Sae-jin
swatchsjp@ajunews.com