Senate majority leader Mitch McConnell began his exceptionally long Capitol Hill career as an intern for one of the lions of the Senate: Kentucky Senator John Sherman Cooper. It happened that McConnell worked with Cooper, an old-school “Party of Lincoln” liberal Republican, during the remarkable era when the senator championed enactment of the Civil Rights Act of 1964 and the Voting Rights Act of 1965.

McConnell has spoken and written at great length about how he was inspired by Cooper’s steady support of civil-rights legislation in the 1960s: “despite the considerable opposition from back home, Senator Cooper never wavered.” In his own memoir, McConnell hailed Senator Cooper’s long and courageous record of advancing “racial equality for every American citizen.”

Cooper did, indeed, act as a “profile-in-courage” senator when he rallied fellow Republicans to support civil-rights legislation, with the argument that it was their historic and moral duty as members of the “Party of Lincoln.” History well records that the courageous Kentuckian played a critical role in organizing most of his party’s caucus to vote with liberal Democrats to avert the stalling tactics of segregationist Democrats, and their conservative Republican allies, so that the Senate could finally speak on behalf of civil rights.

McConnell has always celebrated Cooper’s legacy, and rightly so.

Yet, when a fellow senator invoked the memory of struggles on behalf of racial equality by reading the words of Coretta Scott King on Tuesday night, McConnell and the members of his majority caucus shut her down.

During the Senate debate on the nomination of Alabama Senator Jefferson Beauregard Sessions III to serve as Donald Trump’s attorney general, Massachusetts Senator Elizabeth Warren referred to portions of a letter written three decades ago by Coretta Scott King in opposition to the nomination of Sessions to serve as a federal judge. In that letter, the widow of the Reverend Martin Luther King Jr. recalled how Sessions had as a US Attorney prosecuted voting-rights activists in Alabama and wrote:

Anyone who has used the power of his office as United States Attorney to intimidate and chill the free exercise of the ballot by citizens should not be elevated to our courts.… Mr. Sessions has used the awesome powers of his office in a shabby attempt to intimidate and frighten elderly black voters. For this reprehensible conduct, he should not be rewarded with a federal judgeship.

As Warren was recalling those last devastating words on Tuesday night, McConnell interrupted her and objected that: “The senator has impugned the motives and conduct of our colleague from Alabama…”

A shocked Warren responded: ““I am surprised that the words of Coretta Scott King are not suitable for debate in the United States Senate. I ask leave of the Senate to continue my remarks.” Asserting that the senator who holds the seat once occupied by Edward Kennedy had violated Senate rules against assailing the reputation of a colleague,” McConnell objected. Warren appealed but Montana Senator Steve Daines, who was chairing the Senate session, interrupted her and announced, “Objection is heard. The senator will take her seat.”

A pair of party-line votes supported McConnell’s draconian interpretation of the rules, which if taken to its logical conclusion could effectively silence meaningful debate on any presidential nominee who is a sitting senator.

The majority leader made no apologies for barring Warren—a former Harvard Law School professor and former Vice President of the American Law Institute—from further participation in the Senate debate on whether to make Sessions the next Attorney General of the United States. (McConnell’s Republicans and West Virginia Democrat Joe Manchin cast 52 votes to confirm the Alabaman, while Warren and the rest of the Democratic caucus votes “no.”)

In fact, McConnell claimed that his colleague had to be silenced because: “She was warned. She was given an explanation. Nevertheless, she persisted.”

Those words will be worn as a badge of honor by Warren. Indeed, progressives who hope the senator will seek the presidency in 2020 will undoubtedly employ them as a campaign slogan.

For McConnell, however, there is no honor. The man who holds the seat once occupied by his mentor and hero John Sherman Cooper has used the awesome powers of his office in a shabby attempt to silence the recollection of Coretta Scott King’s warning that entrusting Jeff Sessions to uphold the rule of law would have “a devastating effect…on the progress we have made toward fulfilling my husband’s dream.”

Mitch McConnell has shamed himself and the Senate.

Surely, John Sherman Cooper—who warned that, if the “Party of Lincoln” were ever to align itself with the foes of civil rights, “it will do a great wrong because it will be supporting the denial of the constitutional and human rights of our citizens”—would be horrified by his former intern’s infamy.