The senator long-dubbed "Dr. No" for his ruthless legislative style apologized to colleagues on Thursday even as he implied that Majority Leader Harry M. Reid (D-Nev.) has led the Senate like a tyrant and lectured on how the chamber should operate in his absence.

Of course, he's not gone yet -- and Sen. Tom Coburn (R-Okla.) warned in his closing remarks that he will seek to block or slow debate on several pieces of legislation set for consideration in the chamber's closing days.

The 66-year old senator is stepping down two years short of the end of his current term due to an aggressive recurrence of prostate cancer. He came to Congress as part of the 1994 Republican wave election and joined the Senate in 2005.

The halting, tearful and repeatedly remorseful 27-minute speech included tributes to Coburn's family, personal aides, ushers who run the Senate and staffers at the Government Accountability Office and Congressional Research Service -- two congressional agencies that he's utilized exhaustively over the course of his career. He paused and held back tears when he mentioned his father, who had a fifth grade education and was "a great believer in our country," but "wouldn't recognize it today."

As Coburn spoke at midday Thursday, at least 40 senators sat and watched -- a high level of attendance amid a flurry of closing speeches delivered this week by departing senators of both parties.

In return, he sought forgiveness: "Those of you through the years who I have offended, I truly apologize. And I think none of that was intended -- because I actually see things different. You see, I believe our founders were absolutely brilliant. Far smarter than us."

That launched a passionate tribute to the Founding Fathers, the separation of powers and the unique powers granted to senators.

"I know not everybody agreed with me -- but the one thing I do know is that our founders agreed with me," he added. "They had studied this process before, they knew what happens when you dominate from a central government. And it doesn't mean intentions are bad -- intentions are great, the motivations of the people in this body are wonderful. But the perspective on how we do it and what the long-term consequences of how we do it really do matter."

Coburn said that Americans "need to be supporting and praying for" President Obama, a former Senate colleague with whom he's maintained a close relationship despite sharp ideological differences. Later, he implored Senate leaders to enforce the rules as written.

He read aloud the oath of office for senators and choked up as he read that senators are to defend the U.S. Constitution "and that I will bear true faith and allegiance to the same."

"Your state isn't mentioned one time in that oath," he told colleagues as he slammed his hand on the lectern. "Your whole goal is to protect the United States of America, its Constitution and its liberties. It's not to provide benefits for your state. That's where we differ -- that's where my conflict with my colleagues has come. It's nice to be able to do things for your state, but that isn't our charge. Our charge is to protect the future of our country by upholding the Constitution."

"The magic number in the Senate is not 60," he added. "And it's not 51 -- a majority. The most important number in the Senate is one. One senator. That's how it was set up. That's how our founders designed it. And with that comes tremendous amounts of responsibility, because the Senate has a set of rules -- or at least did -- that gives each individual member the power to advance change or stop legislation. And that's a tool that has to be mentored and refined and wise in its application."

"Every senator has the power to introduce legislation and until recently, offer amendments," he said. "No single senator should be able to decide what the rights of another senator should be. That's tyranny. ... To exercise the rights we've been entrusted with, we must respect the rights of others."

Coburn was referring to how Reid and Senate Democrats have controlled the chamber in recent years by blocking attempts by members in both parties to offer amendments to legislation. But Reid has repeatedly blamed Republicans for blocking legislation and the confirmation of Obama administration nominees and creating the gridlock of recent years.

Despite his formal goodbye, Coburn strongly objects to bills slated for consideration in the coming days, and aides have warned that he will use the procedural tools he praised in his speech to, at a minimum, slow debate of the legislation.

He is opposed to a bill renewing a federally-backed terrorism insurance program because House Republicans included unrelated changes to Wall Street regulations. And Coburn strongly opposes the annual Pentagon policy bill because negotiators included unrelated language authorizing an historic expansion of federally-protected lands, including six new national parks. Coburn also is a longtime critic of excessive federal spending and is likely to vote against the $1.01 trillion spending bill slated for approval.