A year ago, when Gen. Michael V. Hayden last sought Senate confirmation to a new job, protecting Americans' privacy from the global eavesdropping system he had overseen for six years at the National Security Agency was almost an afterthought on Capitol Hill.General Hayden assured senators then that the agency acted "absolutely in compliance with all U.S. law and the Constitution," and sailed to easy confirmation in April 2005 as principal deputy director of national intelligence.
Eight months later, Americans learned that at the direction of President Bush, the N.S.A. had been skirting the law requiring court approval for wiretaps on American soil.
On Thursday, General Hayden again appears before the Senate Intelligence Committee, seeking its approval to add another job, that of director of the Central Intelligence Agency, to a résumé possibly unmatched in the history of American spying.
The question of whether General Hayden misled the committee last year is only one of several that could, in theory, cause trouble. Senators could press him on his role in costly, floundering modernization programs at the N.S.A., or his views on the C.I.A.'s secret prisons for terrorism suspects.
But people who have followed the rise of General Hayden, 61, from blue-collar Pittsburgh through Air Force assignments and into the top jobs in the spy bureaucracy, do not predict a major clash. Through careful cultivation of superiors, Congress and the news media, and a knack for mastery of arcane facts and homespun metaphors, he usually escapes such encounters unscathed.
Former Senator Bob Graham, a Florida Democrat who headed the Intelligence Committee until 2003, recalls coming away dazzled from tours in which General Hayden showed off satellite dishes and supercomputers at N.S.A. headquarters at Fort Meade, Md.
"He builds up your sense of confidence in him as both a visionary leader and one with his mind wrapped around the details," Mr. Graham said.
Brent Scowcroft, under whom General Hayden served from 1989 to 1991 on the National Security Council staff of the first President Bush, also piles on the superlatives.
"He's exceedingly smart, he's very hardworking, he has great integrity, and he knows the intelligence business," said Mr. Scowcroft, himself a retired Air Force lieutenant general who, as chairman of the current president's Foreign Intelligence Advisory Board until 2005, closely followed General Hayden's work at the N.S.A. "That's a combination that's really needed right now at C.I.A."
But Mr. Scowcroft, an experienced judge of Washington insiders, added, "It's easy to snow people on a subject few people know much about."
Whether with substance or with flair, General Hayden began impressing superiors long ago. Dan Rooney, now owner of the Pittsburgh Steelers, coached him when he was a 12-year-old on the football team at St. Peter's Catholic School and quickly picked him out as quarterback.
"He wasn't the biggest or the strongest kid on the team, but he was the smartest," Mr. Rooney recalled. "He exuded confidence, and the other kids gathered confidence from him."
Mr. Rooney later hired the young Mike Hayden, then a student at Duquesne University, to help in the Steelers' front office. But he was as surprised as other friends and relatives when the studious history major chose a military career.
"He was so interested in history that I guess he wanted to become part of it," General Hayden's younger brother, Harry, a truck driver in Pittsburgh, said in an interview last year.
Mr. Hayden's fans in Pittsburgh watched with pride as he rose steadily in the Air Force ranks and became director of the N.S.A., by far the most public chief in the secretive agency's history. He pays regular visits home, seeing the old North Side neighborhood or taking in a Steelers game.
His six-year tenure at the N.S.A., the longest ever, has drawn lavish praise for his undertaking urgently needed change at a time the agency was rapidly falling behind a revolution in communications.
"He changed the culture out there," Mr. Scowcroft said. "Typically, N.S.A. was run by the permanent staff, and directors passed through every couple of years without much impact. He shook it up when it needed shaking up."
That view is widely shared by many government officials. But there is also a pronounced minority view, expressed by some former senior N.S.A. officials and advisers: that General Hayden is better at public relations than at management, and that his record at the agency was far more mixed than his many admirers realize.
"He's masterful at spinning the facts to make himself look good," said one former senior N.S.A. official who worked with General Hayden for several years. Like a number of other critics interviewed for this article, he would not speak for attribution, because he now works for a company that depends on contracts with the N.S.A., the C.I.A. and other intelligence agencies.
The critics, some of whom say they like General Hayden personally and admire his vision, maintain that he showed erratic judgment in crucial personnel decisions and embraced overly ambitious programs that became expensive failures.
Despite the secrecy that hides most of the agency's activities, there is at least some independent evidence to support the critics' claims.
The centerpiece of General Hayden's effort to modernize the agency's technology, a classified program called Trailblazer, ran up bills of more than $1.2 billion and produced few useful results, according to former N.S.A. officials and documents obtained under the Freedom of Information Act. Trailblazer, undertaken in 2001, was intended to improve radically the agency's ability to sort through its haul of intercepted communications, estimated in a 2002 Congressional report at 650 million messages a day.
Another major effort, called Groundbreaker, contracted out the agency's basic computer functions to a consortium of companies starting in 2000. According to N.S.A. officers, the contract produced years of headaches for intelligence officers as they struggled with new software and endured computer crashes. The agency's computer woes were detailed this year in The Baltimore Sun.
In 2003, the Senate Intelligence Committee said in a report that it continued to be concerned with the N.S.A. purchasing process "and frustrated by the lack of progress realized in remedying this problem over the past three years." The same year, Congress stripped the agency of procurement authority over Trailblazer and certain other major classified programs, requiring Pentagon approval of all spending.
General Hayden declined to comment in advance of Thursday's hearing. But in testimony last year, he acknowledged the problems with Trailblazer, describing it as a "moon shot" with excessively ambitious goals. The delays, he said, were even more serious than the cost overruns, which he estimated at "a couple to several hundred million" dollars.
"Hayden had a lot of great ideas," said Matthew M. Aid, a onetime N.S.A. analyst who is writing a history of the agency. "But when he left N.S.A. last year, none of his modernization programs had been completed, and the agency's fiscal management was still broken."
But General Hayden's fans remain loyal. Mr. Graham, who was chairman of the Senate Intelligence Committee when the problems with Trailblazer became evident, said he preferred to attribute the difficulties to worthy ambitions.
"There were failures, but in my judgment they were not failures of competence or management," he said. "When you're Christopher Columbus, you're not going to get to your destination on the first try."