''This is not a complicated deal, and that's why Hillary's opponent can raise a double-ton of money, besides being mayor and having special relations with a lot of those people who have it in New York,'' Mr. Clinton said. ''And you have the right-wing venom machine all geared up against her again.''

The president has taken swipes at Mr. Giuliani in the past, and Mr. Giuliani has relentlessly criticized Mr. Clinton in recent months. But the remarks yesterday were by far the fullest and harshest attack he has offered against the mayor; indeed, they were generally tougher than what Mrs. Clinton herself has been saying during nine months of campaigning in New York.

Mr. Clinton's attack on Mr. Giuliani appeared to be a spontaneous expression of frustration, rather than an orchestrated strategic gambit by Mrs. Clinton's campaign. The $75,000 fund-raiser, which was sponsored by the International Brotherhood of Electrical Workers and held at the Hyatt Hotel on Capitol Hill, was not listed on her public schedule, and her press aides did not accompany her to the event. An accounting of Mr. Clinton's remarks was provided by pool and wire service reporters who routinely accompany the president on his public travels.

The remarks by Mr. Clinton, who has less than 10 months left in the White House, came at a time in which he has appeared increasingly tempted by the campaigning going on at the periphery of his presidency. Earlier this week, in New York, Mr. Clinton offered an attack on George W. Bush, the Texas governor and presumed Republican opponent of Vice President Al Gore for the presidency in November.

''I'm not running for anything,'' Mr. Clinton noted yesterday. ''Most days, I'm O.K. about that.''

More immediately, Mr. Clinton's attack on Mr. Giuliani and his allies came two days after Mrs. Clinton's campaign was startled to learn that it was being significantly outpaced by Mr. Giuliani's in fund-raising. Mr. Giuliani announced this week that he had raised $7 million in the first three months of this year, compared with $4 million by Mrs. Clinton.