Social security and tax reform plans were the main issues of contention Wednesday as opposition party leaders grilled Prime Minister Yoshihiko Noda during a one-on-one Diet debate.

Noda repeatedly urged opposition leaders to cooperate with the passage of the tax hike bill, which he has said will save the social security system by doubling the 5 percent consumption tax by 2015.

At the second one-on-one debate since January, Liberal Democratic Party leader Sadakazu Tanigaki said his party, the largest among the opposition, could not cooperate with Noda’s Democratic Party of Japan unless it is given a detailed schedule of how deliberations on the tax bill will be carried out in the current Diet session, which is scheduled to end June 21.

Noda pointed out that the DPJ and LDP share the same view on the tax hike, as the LDP has stated in its new party pledges for the next election that raising the consumption tax to 10 percent is necessary.

Tanigaki admitted that the LDP and DPJ “share some views” on tax reform but criticized Noda, saying: “The social security and tax reforms are not unified. . . . You won’t be able to gain the public’s understanding.”

New Komeito leader Natsuo Yamaguchi also urged Noda to give detailed plans for social security reform and a specific schedule of deliberations on the tax hike bill.

Noda repeatedly urged both opposition leaders to hold talks, claiming that the administration has cleared all the conditions for cross-party talks suggested by the opposition parties, namely to endorse the reform guidelines and the tax hike bill in the Cabinet.

Tanigaki also asked Noda if he would dissolve the Lower House for a snap election if the tax hike bill is not enacted by summer, since Noda has said he will “risk his political career” for the bill’s passage. But Noda was noncommittal, saying, “I am determined (to pass the tax hike bill).”

On Monday, Noda requested opposition party leaders hold one-on-one talks with him on the DPJ’s social security and tax reform plan before Wednesday’s debate. The LDP and New Komeito turned down the request, countering that holding talks before the debate would be unusual and that an open discussion in the Diet was better.

Opposition support is critical to the DPJ’s efforts to pass bills because they hold a majority in the Upper House.

Elsewhere, the opposition camp decided Wednesday to request that former Prime Minister Yukio Hatoyama — who recently made a controversial private visit to Iran — appear before the Lower House Budget Committee as an unsworn witness.

Hatoyama was quoted by Iranian national television as criticizing the International Atomic Energy Agency for applying a double standard to the country. He later denied making the statement.

Opposition parties have criticized the government and the DPJ for not preventing Hatoyama’s trip, which they have called damaging to national interests.