When George Tenet (search) wraps up his duty at the CIA in July, he will have achieved something very few people at the highest stage of government have done by working for both Republican George W. Bush and Democrat Bill Clinton.

Tenet's last day will be July 11 — seven years to the day after he became Clinton's director of Central Intelligence. He took the job after spending two years as the CIA's deputy director.

Hit by criticism of the CIA's pre-war intelligence estimates, Tenet found himself frequently on the defensive. In February, he went to Georgetown University and made a major speech defending his agency, making the point that intelligence gathering involves sophisticated guessing many times.

"Did these strands of information weave into a perfect picture? Could they answer every question? No, far from it. But, taken together, this information provided a solid basis on which to estimate whether Iraq did or did not have weapons of mass destruction (search) and the means to deliver them. It is important to underline the word estimate. Because not everything we analyze can be known to a standard of absolute proof," he said.

Tenet already had dodged a few potentially career-ending moments on his watch.

In 1998, Israeli officials tried to pressure the United States into releasing convicted spy Jonathan Pollard (search). Tenet threatened to resign if Clinton went along with the Israeli demands and Clinton would only call for a review of Pollard's case.

The next year, on May 7, 1999, intelligence failures led to what Tenet and other U.S. officials said was the accidental bombing of the Chinese Embassy in Belgrade during the Kosovo war.

Earlier this year, famed Pakistani scientist A.Q. Kahn (search) disclosed that he sold certain nuclear technologies to Iran, Libya and North Korea. The news prompted U.S. lawmakers to wonder why the CIA didn't know about what Kahn was doing.

But the biggest challenges Tenet faced were the Sept. 11, 2001, attacks on the United States and the build-up to the second U.S.-led war against Iraq.

In the case of the former, officials wanted to know why the American intelligence community didn't know about the coordinate attacks that killed nearly 3,000 people. While in the second, lawmakers asked if Tenet and the CIA misled the Bush administration with intelligence that suggested Saddam Hussein had weapons of mass destruction — weapons that largely have not been found.

A number of primarily Democratic lawmakers publicly called for Tenet's resignation, especially  following the Iraq war.

During his speech to CIA employees Thursday announcing his plans, Tenet sought to point out the positive aspects of his tenure. Tenet said the CIA had made good progress at rebuilding its clandestine service, improving training and recruitment, and developing new technologies.

"Our record is not without flaws. The world of intelligence is a uniquely human endeavor and as in all human endeavors, we all understand the need to always do better. We are not perfect but one of our best kept secrets is that we are very, very, very good," Tenet said.

Fox News' Brian Wilson contributed to this report.