ROBERT GATES, President Bush's nominee to head the CIA, was praised by a key senator at the close of his confirmation hearings.Mr. Gates rebutted claims that he knew more about Iran-contra than he has admitted and allegations that he slanted intelligence to suit President Reagan's rigid anti-Soviet ideology. Sen. David Boren (D) of Oklahoma, chairman of the committee, opened the session Friday with glowing praise for Gates, a senior CIA official in the 1980s and now White House deputy national security adviser. Senator Boren said there is "no single person" in the US intelligence community who has been more committed to the congressional oversight process and sharing data with Congress. Sen. Howard Metzenbaum (D) of Ohio asked how Gates could have produced a detailed defense against 20 allegations of politicizing intelligence in the 1980s after the nominee, in earlier statements to the panel, repeatedly said he could not remember details of Iran-Contra events. Gates said he was able to mount a detailed defense against charges of slanting intelligence after CIA officials produced a stack of documents relating to the claims. No such evidence remains relating to Iran-contra, he said. The committee is slated to vote on the nomination in two weeks.