Prime Minister Shinzo Abe's long-held goal of amending Japan's Constitution by 2020 appeared in tatters Monday, after the ruling coalition and pro-revision parties failed to capture the two-thirds supermajority needed to move the revision forward in the Upper House election held the previous day.

With the ruling Liberal Democratic Party and Komeito, along with pro-revision Nippon Ishin no Kai, securing only 157 of the 164-seat two-thirds supermajority needed to set in motion a national referendum on the issue, Abe had little choice but to extend an olive branch Monday in the hope of finding allies in other parties.

At a news conference Monday afternoon, Abe began with criticism of the opposition — saying that over the past year, constitutional revision was only discussed for two hours in the Lower House and three minutes in the Upper House. But he then called on all parties to submit their own proposals.