Thorough Probe of CIA Nominee Vowed : Intelligence: A Senate committee chairman sees a number of ‘tough questions’ facing the President’s choice. The hearings open today.

The chairman of the Senate Intelligence Committee vowed Sunday that his panel will subject Robert M. Gates, President Bush’s choice to head the Central Intelligence Agency, to be “one of the most thorough” examinations in congressional history.

“There are a lot of tough questions that are there to be asked,” said Sen. David L. Boren (D-Okla.) as the committee prepared to open this morning what could prove to be highly sensitive hearings on the controversial nomination.

The committee is expected to question Gates about his role in the Iran-Contra affair, which he maintains was negligible, and about allegations that he slanted an intelligence assessment of the 1981 assassination attempt on Pope John Paul II to suggest it was masterminded by the Soviet KGB. He is also likely to face questions about his involvement in secret U.S. policies to provide military aid to Iraq during its war with Iran.

Boren pledged that his committee will not vote on his nomination “until we’ve been satisfied with those answers.”

The strong language from the influential chairman raised the possibility that the committee might seek to prolong its inquiry in a fashion that White House officials have warned could leave the nominee to “twist in the wind.”

Asked whether he had urged the White House to withdraw Gates’ name from consideration, Boren, who is usually thought to be supportive of the nominee, said he had not, but added: “That’s a decision that the President has to make.”

Speaking in an interview on ABC-TV’s “This Week With David Brinkley,” Boren said that it remained “hard to say” whether new evidence would cause the committee to reject the nomination. Administration officials nevertheless expressed continued assurance that the nominee would win a Senate endorsement.

“I am confident that Mr. Gates will be confirmed,” National Security Adviser Brent Scowcroft said on the same broadcast. And President Bush told reporters Sunday he felt “very strongly” about the Gates nomination and predicted: “He’ll pass.”

Among the potentially explosive new accusations senators said the committee will attempt to probe are charges by Sen. Bill Bradley (D-N.J.) that Gates was involved during the mid-1980s in secret and improper CIA operations to provide military aid to the Iraqi regime of Saddam Hussein.

“The question is whether what he did and what he was aware of was fully authorized by law,” Bradley said on CBS-TV’s “Face the Nation.”

A source close to Gates declined Sunday night to discuss details of his involvement in the U.S. support for Iraq, the full extent of which has not been made public and is understood to remain so highly classified that it may only be raised in closed hearings this week.

But the source said in defending the nominee: “I think you’ll find that everything that happened was legal.”

At the same time, other senators made clear that they intend to probe Gates aggressively about what Boren called “certainly serious charges” made in recent weeks by Alan D. Fiers, a former CIA official.

Fiers is expected to testify Thursday that he and other senior CIA officials were aware months before the scandal broke in 1986 of the secret diversion of profits to the Nicaraguan rebels from the sale of U.S. arms to Iran.

The allegation, together with other new accounts, raise questions about Gates’ avowals before the Senate committee after he was first nominated to the CIA post in 1987 that he had not known about the illegal operation until its details became public.

Gates himself withdrew from consideration for that job after senators expressed doubt about that statement. And with questions on the extent of Gates’ knowledge about the Iran-Contra scandal expected to dominate the hearings, both critics and supporters of the nominee agreed Sunday that Gates’ hopes for confirmation would collapse if he were shown to have been less than truthful in his answers about that affair.

“I think we’re going to be interested in judging not only the letter of what he says, but the spirit of what he says, whether he’s really being candid with us or not,” Boren said in the ABC interview.

In advance of the hearings, which are expected to last at least a week, members of the committee said they hoped to scrutinize details about Gates’ past performance that have long been shrouded in mystery, in large part because of the nature of sensitive positions he has held within the intelligence community.

But Boren conceded that among the mysteries the panel cannot hope to resolve is evidence that may have been assembled against Gates by the independent prosecutor who is looking into allegations of wrongdoing related to the Iran-Contra affair.

The prosecutor, Lawrence E. Walsh, has confirmed that Gates is a “subject” of the probe--a status less serious than that of a formal “target”--but has declined to provide the committee with further details about the nominee on grounds that it could jeopardize his own investigation.

“We really can’t know what he knows at this point,” Boren said of Walsh.

Other senators expressed frustration that their efforts to publicly question Gates about cases in which the nominee appeared to have modified intelligence reports to fit a political agenda would be limited because those CIA documents remain classified.

Among the allegations sources said the senators may be forced to explore only in closed session is the contention that Gates as a senior CIA official in the mid-1980s slanted an assessment of the 1981 assassination attempt on the Pope.

“I think there is information there that Robert Gates should have to explain,” Sen. Dennis DeConcini (D-Ariz.) said on CNN’s “Newsmaker Sunday” of what he described as “a number of classified examples” in which Gates appears to have politicized intelligence.

The senator suggested that such evidence will include new revelations about Gates and said he saw no reason that it should remain classified. But, for now, he said: “I can’t talk about it.”