Sen. Robert Byrd (D-W.Va.), one of the most colorful, respected Members of Congress, marked a new milestone Monday, when he became the third longest serving lawmaker in U.S. history.

“I am very proud of my record of service in the U.S. Congress,” Byrd, 85, said in a statement, adding that this is something he never imagined would happen to him. “This is a great accomplishment, one that I could not have reached without the decades of support from the men and women of West Virginia.”

In marking his 50th year, second month and 14th day of service on Monday, the West Virginian moved past the late Rep. Carl Vinson (D-Ga.).

Out of the 11,707 Members in history, only two others have served longer than Byrd: Jamie Whitten (D-Miss.), who served in the House for 53 years, two months and 13 days, and Carl Hayden (D-Ariz.), who served in the House and the Senate for a combined total of 56 years, 10 months and 28 days.

Minority Leader Thomas Daschle (D-S.D.) paid tribute to Byrd on Monday.

“I come to the floor today to congratulate Senator Byrd on reaching this historic milestone and to thank him for the many lessons he has taught me and for the kindnesses he has shown me over these many years,” Daschle said.

He later spoke of Byrd’s famous dedication to the Constitution: “In these anxious days, when some argue that the United States must curtail some of our constitutional rights, or rewrite the balance of powers in our government, Robert Byrd reminds us that principled compromise is a worthy goal — but our basic constitutional principles themselves must never be compromised.”

After three terms in the House, Byrd was elected to the Senate in 1958. His tenure in that chamber has included terms as Majority and Minority Leader, as well as two stints as chairman of the Appropriations Committee.

He also served as President Pro Tem twice, placing him third in line for the presidency from 1989 to 1994, and again from June 2001 to 2002.

“If any lesson can be taken from my more than five decades of service, it is that, for our country to weather the difficult seas ahead, we in Congress must exercise our most tempered judgments and seek our most noble instincts,” Byrd said.