The 147th ordinary Diet session was convened Thursday, as the ruling and opposition camps brace to do political battle over a controversial proposal to cut the number of seats in the Lower House and an expansive 84.99 trillion yen budget for the fiscal year. The current Diet session is scheduled to last 150 days, unless Prime Minister Keizo Obuchi exercises his right to dissolve the Lower House. Both the Upper and Lower Houses on the same day set up special committees to review the Constitution for possible revision. The Lower House panel consists of 50 lawmakers, who formally approved the appointment of Liberal Democrat Taro Nakayama as the panel's chairman. The Upper House panel consists of 45 members. Masakuni Murakami, another Liberal Democratic Party member, was appointed chairman. They are the first panels of their kind since the enactment of the war-renouncing Constitution following World War II. "The mission tasked to this committee is extremely grave," Nakayama told the first ceremonial session marking the opening of the panel. Discussing revisions to the Constitution has long been taboo among politicians given the dark memories of the military regime before the end of the war. Murakami told reporters that he is "deeply moved" that the taboo has now been lifted more than 50 years after the end of the war. The presidents of three opposition parties -- the Democratic Party of Japan, Japanese Communist Party and Social Democratic Party -- held a meeting before the opening of the Diet session to confirm their agreement to jointly confront the ruling coalition over the seat-reduction bill. They called for sufficient deliberation on the bill, pledging they "will never allow" the ruling coalition -- the LDP, Liberal Party and New Komeito -- to enact the planned legislation at the beginning of the Diet session. The opposition parties also pledged to jointly confront the LDP over its financial scandals and the fiscal 2000 budget, which they argue is too dependent on huge issues of national bonds. DPJ Diet affairs chief Tatsuo Kawabata said the party may refuse to attend Diet deliberations if the ruling camp tries to ram the seat-reduction bill through. "This Diet session will be extremely rough from the beginning," DPJ President Yukio Hatoyama also warned. If the opposition parties boycott all Diet sessions to protest the proposed seat-reduction plan, the legislature could be paralyzed and the prime minister may have no choice but to dissolve the Lower House to break the deadlock, observers said.