Japan's Prime Minister Shinzo Abe addresses reporters on the first official business day of the New Year during a news conference at his official residence in Tokyo, Japan, January 4, 2016. REUTERS/Toru Hanai

TOKYO (Reuters) - Japanese Prime Minister Shinzo Abe said on Sunday he aimed to get a two-thirds majority from his ruling bloc and like-minded opposition parties at an upper house election this summer to enable him to revise the constitution.

Abe has made clear he wants to revise the U.S.-drafted, pacifist constitution, but formal amendment requires approval by two-thirds of both houses of parliament and a majority in a referendum.

Abe’s Liberal Democratic Party (LDP) and its junior coalition partner, the Komeito party, already command a two-thirds majority in the lower house, but only hold a simple majority in the upper chamber.

“It will be very difficult for the ruling bloc alone to win a two-thirds majority,” Abe told a TV news program.

“Besides the LDP and Komeito, I aim to form a two-thirds majority with those positive and responsible people who are thinking of a constitutional revision.”

Abe mentioned “Osaka Ishin No Kai”, or the Osaka Innovation Party, as one possible partner backing the revision.

Admirers view the constitution as the source of Japan’s peace, prosperity and democracy.

Many of Abe’s conservative backers, who have long wanted to rewrite the constitution but lacked the political means, view it as a shoddy document written, in the words of one commentary, “with malice and vengeance” to keep Japan forever subdued.

A change proposed by the LDP would make clear Japan has the right to maintain a military and deploy it at home and abroad, but Abe said debate would probably deepen as to which chapter of the constitution should be revised.