Sen. Jon Tester (D., Mont.) referred to former Democratic senator and ex-Ku Klux Klan member Robert Byrd as a "great" senator during a Senate floor speech on Thursday. Tester was discussing the government shutdown as he made his remarks.

"We can continue to have the debate about the best way to secure the border, but it should not be done holding the American people hostage. It should be done by having the debate that this body, the most deliberative body in the world I was told before I got here — got to serve with great senators, got to serve with Robert C. Byrd and Richard Lugar and Kennedy and Baucus, the list goes on and on. We don't debate. We don't even vote," said Tester.

Byrd, who served as a West Virginia senator from 1959 to 2010, joined the KKK at age 24 and led his local chapter in the rank of Exalted Cyclops. In the 1940's, Byrd refused to join the military because he feared serving with "race mongrels, a throwback to the blackest specimen from the wilds," according to a letter he wrote at the time.

In 2001, Byrd stirred controversy after he used the term "white niggers" in an interview, saying, "I've seen a lot of white niggers in my time." Byrd apologized for the remarks, but NAACP president Kweisi Mfume called them "both repulsive and revealing," adding that "any progress he has made on race is relative."

Tester is not the first Democratic senator to speak positively of Byrd in recent years. In 2013, former California senator Barbara Boxer called Byrd "one of the great senators and historians," praising him because he "always tells us to read the Constitution."