Sen. John Ensign (R-Nev.) gave a farewell speech on the Senate floor Monday in which he apologized to his colleagues for having an affair with a campaign aide and warned other senators to guard against the strain of self-importance that led him to stray from his beliefs.

Ensign, who will resign May 3, said when he first arrived in the Senate, he saw people who were caught up in self-importance and never saw himself sliding in the same direction.

"As easy as it was for me to view this in other people; unfortunately, I was blind to how arrogant and self-centered that I had become," Ensign said. "I did not recognize that I thought mostly of myself.

"The worst part about this is, I even tried not to become caught up in my own self-importance," he continued. "Unfortunately, the urge to believe in it was stronger than the power to fight it. This is how dangerous the feeling of power and adulation can be."

Ensign urged other members to "surround yourself with people who will be honest with you," and then make them promise to "not hold back, no matter how much you may try to prevent them from telling you the truth." He said he wished he had done this earlier, and added that this is "one of the hardest lessons that I've had to learn."

He also said he regretted his earlier decisions to judge Sens. Larry Craig (R-Idaho) and Ted Stevens (R-Alaska). He said that while he first called on both to resign, he later told both that he was wrong to make this call. Craig resigned over the infamous foot-tapping bathroom scandal, and Stevens was charged with corruption but not convicted.

The resigning Nevada senator said that when news of his infidelity broke in 2009, Craig was the first to call and offer support.

"Each of these men were gracious enough to forgive me, even though publicly I didn't show them the same grace," Ensign said. "The purpose of me speaking about this is to humbly show that in life, a person understands mercy a lot more when they need it, and when it is shown to them."

Ensign closed by apologizing to his colleagues, and his wife and family.

"To my Senate colleagues, I would like to take a moment to apologize for what you have had to go through as a result of my actions," he said. "I know many of you were put in difficult situations because of me, and for that I sincerely apologize."

About his wife Darlene, he said, "I do not deserve a woman like her, but I love her and I'm so grateful that the Lord has put her in my life."

Ensign's last day in the Senate is Tuesday.