A senior U.S. official today said President Clinton's plan to give Sinn Fein leader Gerry Adams a warm White House reception Friday represents a leap of faith that risks upsetting the delicate peace between Britain and Northern Ireland. In testimony before a House committee, Assistant Secretary of State Richard Holbrooke added that the onus is on Adams to make sure he doesn't go too far while trying to raise money in the U.S. "The president has taken a risk on behalf of peace by permitting limited fundraising by Sinn Fein," Holbrooke said. "The ball is in their court now to show that they are serious about removing the gun from the political arena in Northern Ireland." Adams, who just 13 months ago was barred from entering the United States, spent the day paying courtesy calls on members of Congress, then hosted a $200-a-plate lunch in New York that drew celebrities and politicos including Bianca Jagger, Tom Hayden and former Mayor David Dinkins. Expected haul: $80,000.