The White House and Democratic National Committee said the party returned Mr. Cabrera's $20,000 in October, after deciding it was an improper donation.

Most of the improper donations were solicited by Mr. Huang.

The note was delivered by Mark Middleton, a former White House aide who has denied accusations that he, too, tried to solicit improper donations from abroad.

Mr. Gore's staff returned many of the improper donations, and some Asian-Americans say they detect a reluctance on his part to be identified too closely with them.

Mr. Kanemaru pleaded guilty in September to accepting an improper $4 million political donation from a trucking company with ties to organized crime.

The Democratic National Committee has already returned about $1.5 million in improper donations and has started its own review of recent fund-raising.

While announcing new restrictions on fund-raisers to avoid more improper donations, Mr. Romer and other party officials offered only vague explanations for returning much of the money.

Mr. Karl has also been enmeshed in accusations that he made improper donations to Gary Hart's Presidential campaign.

Mr. Karl has been linked in news reports to improper donations to the Presidential campaign of Gary Hart.

They have figured prominently in the inquiries and are suspected by law-enforcement officials of being conduits for improper donations.