WASHINGTON (AP) _ The Senate's investigation into campaign finance abuse should look into Republican assistance to a Japanese-American businessman who contributed $500,000 to the party, a key Democrat said Monday.

Sen. Carl Levin, D-Mich., said Michael Kojima should be a focus of the investigation because a Republican campaign official in 1992 wrote Japan's prime minister on his behalf after he pledged $500,000 to the party.

The donation embarrassed Republicans when it was learned Kojima had large unpaid debts and failed to make child-support payments.

Kojima, president of a Los Angeles company, got a seat near then-President Bush at a Republican dinner for his large contribution.

Levin handed out a March 9, 1992, letter from a Republican Party official to then-Japanese Prime Minister Kiichi Miyazawa on Kojima's behalf. The letter's author, Lisa DeGrandi, was head of the Presidential Roundtable _ a GOP senatorial campaign group for major party contributors.

Several weeks earlier, Kojima received a thank you letter from former Sen. Howard Baker, who was chairman of the dinner. He thanked the businessman ``for agreeing to serve as a co-chairman by pledging $300,000 to The 1992 President's Dinner.'' Dinner officials later said the contribution was $500,000.

The Senate has approved an investigation into political fund-raising problems in both parties, and Levin is trying to ensure that the bipartisan scope turns into reality when hearings begin.

``We need a bipartisan investigation and a bipartisan remedy'' to campaign finance abuse, said Levin, a member of Sen. Fred Thompson's Governmental Affairs Committee. Levin discussed the investigation with a group of reporters, even questioning whether the donated money could have originated with a loan from the Lippobank.

The bank is part of an Indonesian conglomerate controlled by the Riady family that is a focus of investigations into White House fund-raising.

DeGrandi wrote the Japanese prime minister on March 9, 1992, to thank him for meeting with Kojima while he was in Japan. She said his firm ``does significant business throughout the international arena'' and described him as ``one of our executive members of the Presidential Roundtable, a business advisory group that advises members of the U.S. Senate, President Bush and the administration on business issues.''

The letter also mentioned that Kojima ``met with President Bush at the White House'' and would soon meet with Chinese leader Deng Xiaoping.

Levin asked, ``Were appointments made for Kojima in Japan by the U.S. embassy?''

Levin said the committee has been unable to locate Kojima. Attempts to find a telephone listing were unsuccessful.

The Associated Press reported from Tokyo in May 1992 that Kojima used his GOP connections to receive unusual assistance for a business consortium from U.S. diplomats.

Government officials and businessmen in Tokyo in 1992 said Kojima had carried with him a photo of himself with Bush at the White House and a sheaf of testimonial letters from Republican politicians.

The Republican Party placed Kojima's $500,000 contribution in escrow following a report by the AP that Kojima was indebted for hundreds of thousands of dollars in child support and unpaid loans. In fact, after his donation, he was arrested for failing to make child-support payments.

The money became the subject of litigation, with creditors seeking the funds from the dinner committee.

The case was settled out of court, with Republican campaign organizations keeping $215,000. The remainder went to three creditors _ a former wife of Kojima, a limited partnership and Lippobank, which had a two-year judgment against him for nearly $600,000. A bank attorney had stated the loan and the contribution were several years apart and not related.

Levin said a committee subpoena asked Republican Party officials to turn over any information on Lippo and Kojima to determine whether the bank's loan was related to the contribution.

The White House, meanwhile, said it was reviewing the practice of National Security Council officials speaking to Democratic Party donors on foreign policy. The practice came under review after Democratic National Committee documents showed that Nancy Soderberg, a senior NSC official, had briefed donors or attended fund-raising dinners.

Soderberg spoke in 1995 to the Democratic Business Council about foreign policy, according to documents released last week by the DNC.

Such meetings usually featured a string of administration speakers, who briefly outlined administration policy in their particular area of expertise, said NSC spokesman David Johnson.

National Security Adviser Samuel Berger is reviewing the practice to determine ``whether we want to continue it,'' Johnson said.

``It is important for people who work here to have opportunities to talk to people and the public about their ideas and to provide them information on the president's foreign policy,'' he said. ``Whether or not this is the right vehicle for it is something we are looking at.''