A day after Prime Minister Yoshiro Mori's apology before the Diet appeared to alleviate the chaos over the resignation of a scandal-tainted Cabinet member, the opposition shifted its target Tuesday to the ruling Liberal Democratic Party's dubious election roster system.

The opaqueness of the process by which the LDP ranks candidates for its proportional representation roster for House of Councilors elections was suddenly exposed after former Financial Reconstruction Commission chief Kimitaka Kuze stepped down Sunday for having received millions of yen in benefits from private firms.

Kuze, an Upper House member of the LDP, indicated upon his resignation that he needed the 100 million yen provided by condominium builder Daikyo Corp. in 1991 to have his name placed higher on the party's proportional representation roster for the 1992 election.

A former Daikyo president, who was also a senior member of one of Kuze's support groups, footed the bill for the annual membership fees of 33,000 LDP members, many of whom apparently did not join the party voluntarily.

"The LDP's system requires candidates (in the proportional representation segment of Upper House elections) to recruit an enormous number of new party members and have their support groups provide funds," Kuze said. "I have suffered under that system, trying to keep myself listed high enough (on the roster) to be assured victory."

Under the current election system, political parties draw up a roster of candidates ahead of the start of formal campaigning.

Citizens vote for the party of their choice and the number of votes won garnered by a party proportionally determines how many of its candidates gain a Diet seat.

According to the LDP's election affairs office, a hopeful candidate must recruit at least 20,000 new party members as a condition for his or her name to be listed on the party's proportional representation roster in an Upper House election.

Furthermore, if a candidate has more than 1 million supporters, it is a plus factor in determining the candidate's position on the list, office personnel said.

The opposition camp on Tuesday stepped up its criticism of the LDP's roster system, calling it a "hotbed of back-scratching alliances between politicians and businesses."

"This system could eventually lead to buying Upper House seats with money," charged Tsutomu Hata, secretary general of the main opposition Democratic Party of Japan.

Hata, a former LDP member until he bolted in 1993, said the same system existed while he was with the party. However, the task of recruiting new party members imposed on LDP candidates seems to be getting even stiffer now, he said.

Norihiko Narita, a professor of political science at Surugadai University, suggested that the LDP change its current system, which forces individual candidates to collect party membership fees or shoulder them personally in order to be listed higher on the proportional representation roster.

But Narita, who served as a parliamentary secretary to former Prime Minister Morihiro Hosokawa, added that a system that does not list candidates in any order, as is the case in many European nations, could lead to fiercer and costlier campaigning by candidates -- who would then have to campaign nationwide -- and possibly lead to greater collusion among candidates and major vote-generating organizations.

With the next Upper House elections to be held next summer, calls for the widely criticized LDP system to be reviewed are emerging even from within LDP party ranks.

Senior members of an LDP faction led by Mori and another led by former secretary general Koichi Kato met Monday night and agreed that the current Upper House proportional representation system should be revised so that voters cast ballots for a particular candidate rather than a party, so that winners are chosen based on the number of votes they receive as individuals.

Mori, however, is reluctant to upset the current system. The prime minister told reporters Tuesday that he has no intention of reviewing the current LDP rules, adding that the current system is the fruit of years of party contemplation.