WASHINGTON (AP) — Sen. Tom Coburn, leaving office early as he battles cancer, bade an emotional farewell to his colleagues Thursday, urging them to limit government's power and protect Americans' liberty.

Coburn is an Oklahoma doctor who began his congressional career in the House in the 1994 election known as the Republican Revolution. An outspoken conservative and a crusader against wasteful spending, he earned the nickname "Dr. No."

Speaking on the Senate floor, Coburn offered his apologies "to those of you through the years who I have offended." He said his criticisms were never personal but he spoke out because "I purely believe that freedom gains us more than anything we can plan up here."

Senators from both parties rose to praise Coburn's willingness to listen and ability to forge smart, bipartisan agreements.