A year to the day after President Clinton named him to be U.S. ambassador to the United Nations, Richard C. Holbrooke apologized yesterday for what he called bookkeeping lapses that led to an ethics investigation and delayed his taking the post.

Holbrooke's humility on the first day of hearings by the Senate Foreign Relations Committee on his nomination appeared to placate the committee's powerful chairman, Sen. Jesse Helms (R-N.C.), and to clear the way for his confirmation, perhaps before the Senate's July Fourth break, committee members and staff aides said.

"I believe we're getting somewhere, Mr. Holbrooke," Helms said after listening to Holbrooke's apology.

No committee member other than Helms directed any criticism at Holbrooke, 58, an investment banker and former assistant secretary of state who was the principal architect of the 1995 peace agreement for Bosnia. Several senators instead turned their fire on what they said were the confusing ethics laws and lengthy investigations into anonymous allegations that tangled up Holbrooke's appointment.

Senate Armed Services Committee Chairman John W. Warner (R-Va.) introduced Holbrooke as "eminently qualified" and "distinguished," although he said Holbrooke had made "some errors" on ethical points. Two key Republican senators, Richard G. Lugar (Ind.) and Rod Grams (Minn.), also said they would support Holbrooke.

The Republicans joined Democrats in saying that Holbrooke, a renowned arm-twister, has the rare skills needed to persuade the U.N. General Assembly to undertake the budget cuts and bureaucratic streamlining that Congress is demanding as a condition for paying $1 billion or more that the United States owes the United Nations.

Helms opened the hearing with a denunciation of Holbrooke's practice of inviting U.S. ambassadors to his meetings with foreign officials when he was traveling on private business after leaving the State Department. Mounted on an easel was a chart showing that Holbrooke's employer, the investment bank Credit Suisse First Boston Corp., paid $21,805 in travel expenses on trips in which, according to Holbrooke, no bank business was conducted.

"I suppose we must conclude that CSFB was simply being a good corporate citizen, underwriting Mr. Holbrooke's diplomacy on behalf of the American government," Helms said.

Holbrooke paid a $5,000 fine in February to settle Justice Department civil allegations that he violated lobbying laws by mixing bank business with his role as an unpaid U.S. diplomatic envoy.

"I knew the law and I was careful to follow it," Holbrooke said yesterday. "But I think I did not realize how complicated it would be to avoid misperceptions in some areas, at some times, because of the two roles, which were different."

"With regret," he added, "I must say that carelessness on occasion on my part contributed to these misconceptions. I recognize further that my record keeping and bookkeeping was inadequate at times. . . . I apologize to the committee and to its staff for any inconvenience I may have caused" in obliging them to review thousands of pages of documents about his case from the Justice Department and the State Department's inspector general.