A stern Senate speech didn’t stop Joseph McCarthy. It won’t stop Trump.

In a dramatic speech Tuesday, Sen. Jeff Flake, R-Ariz., announced that he would not be running for re-election. Pointedly, Flake denounced the dark turn that American politics had taken in the age of President Trump and decided he wanted to be no part of it. With his principles at odds with his president and his party, Flake insisted he had no choice. “Acting on conscience and principle is the manner in which we express our moral selves,” his remarks read, “and as such, loyalty to conscience and principle should supersede loyalty to any man or party.”

Margaret Chase Smith

Flake’s speech, in both its tone and topic, calls to mind a famous forerunner: Sen. Margaret Chase Smith’s “Declaration of Conscience” address, given in the same chamber on June 1, 1950.

Like Flake, Smith, R-Maine, spoke to denounce a demagogue in her own party and to announce her refusal to stand quietly by as he did damage to the nation’s institutions. Smith’s target – unnamed in her speech, much as Trump was unnamed in Flake’s – was none other than the junior Republican senator from Wisconsin: Joseph R. McCarthy.

A few months earlier, in February, McCarthy had set the political world on fire with his stunning accusation that there were 205 “known communists” working in the Truman State Department. Challenged on his charges, McCarthy repeatedly refused to offer any proof; indeed, in later versions of the speech, he even changed the alleged number several times over. But no matter. McCarthy’s charges made for spectacular headlines and, as he discovered, fame brought with it a rise in his political fortunes.

For his Republican colleagues in the Senate, McCarthy posed a bit of a problem. The Republican Party had been wandering in the political wilderness for the previous two decades, cast away by voters who blamed them for the Great Depression and rallied to the party of Franklin D. Roosevelt during the New Deal and World War II. At long last, McCarthy had provided a popular cause that might let them tear down the Democrats and build themselves up instead. For some partisans, any attack that worked was welcome. But others were increasingly troubled by McCarthy’s attacks, especially when he repeatedly refused to back up his claims with any proof.

Though she was a freshman senator, and the only woman in a male-dominated body, Smith decided she had to speak out. (As she made her way to the chamber, she ran into McCarthy himself on the Senate subway. “Margaret, you look very serious,” he joked. “Are you going to make a speech?” “Yes,” she shot back, “and you will not like it!”)

Joseph R. McCarthy

With McCarthy and their colleagues arrayed around her, Smith noted with sadness that the Senate had been “debased” in recent months by a new politics of “hate and character assassination.” “I think that it is high time for the United States Senate and its members to do some soul-searching – for us to weigh our consciences – on the manner in which we are performing our duty to the people of America,” she announced.

Smith was, as she noted in her remarks, a loyal Republican and a proud partisan, one who had criticized Democrats repeatedly in the past and would continue to do so. But partisanship had its limits, she insisted: “I don’t want to see the Republican Party ride to victory on the Four Horsemen of Calumny – Fear, Ignorance, Bigotry, and Smear.”

Speaking out against McCarthyism was a patriotic duty for all good Republicans, Smith asserted, in part because McCarthy had presented his own actions as patriotic. “Those of us who shout the loudest about Americanism in making character assassinations,” she said, “are all too frequently those who, by our own words and acts, ignore some of the basic principles of Americanism: The right to criticize; the right to hold unpopular beliefs; the right to protest; the right of independent thought.”

As her 15 minutes came to a close, Smith introduced into the record a formal “Declaration of Conscience” signed by her and six colleagues. “We are Republicans,” the statement began. “But we are Americans first.” Whatever their party loyalties, their principles and their patriotism forced them to speak out against the divisive “totalitarian techniques” of McCarthyism, “techniques that, if continued here unchecked, will surely end what we have come to cherish as the American way of life.”

The Senate was largely stunned by the speech. Most expected McCarthy to return the attack with his usual ferocity, but he glared at the back of Smith’s head for a while and then abruptly stormed out of the chamber. A few colleagues muttered comments of support, but the Republican leadership largely looked the other way.

The political press, already on edge over McCarthy’s crude attacks, lavished Smith’s principled stand with praise. In the pages of The Washington Post, legendary political commentator Walter Lippmann, who had coined the term “Cold War,” hailed her “noble declaration” for bringing dignity to the fight. Bernard Baruch, another elder statesman, declared that had a man given that speech, “he would be the next president.” Newsweek set its sights only slightly lower, running a cover story headlined “Senator Smith: A Woman Vice President?”

Despite the widespread praise, Smith’s declaration did nothing to stop McCarthy. Publicly, the Wisconsin Republican continued to ignore her. When pressed, he responded, “I don’t fight with women senators.” Privately, McCarthy mocked Smith and her supporters as “Snow White and the Six Dwarfs.” One of the men who signed Smith’s Declaration, he joked, had been caught “speaking through a petticoat.” Within weeks, the debate over the Declaration of Conscience was swept aside by the outbreak of the Korean War. With a new Cold War crisis abroad, McCarthy and McCarthyism grew steadily stronger at home. Emboldened by his re-election that fall and the electoral success of his supporters, too, McCarthy finally had his revenge in 1951. He kicked Smith off the prized permanent investigations subcommittee he chaired, replacing her with a Republican rising star who shared his anti-communist commitments: Richard M. Nixon, then a senator from California.

With his handful of Republican critics now cowed into silence, McCarthy had free rein for the next four years. During that time, he inflicted incalculable damage to American political culture and political institutions. Eventually he overreached, attacking the U.S. Army as a source of subversion. When he did, the remainder of the Senate finally found the courage that Smith and her allies had shown four years earlier and acted against him, with formal censure in December 1954 and unofficial ostracism from then on.

Today, Smith’s “Declaration of Conscience” stands as a piece of stirring rhetoric, but also a stark reminder that words can do only so much. It is not enough to speak out against threats to the nation, to give voice to one’s conscience. Convictions ultimately mean little if there are no actions to match them.

Flake’s words echo Smith’s, but they ultimately ring even more hollow. Though Flake has spoken out against Trump consistently, he has also regularly voted to support the president’s agenda on issues ranging from health care repeal to the budget to the Supreme Court. Indeed, only hours after his principled stand in the Senate, Flake fell back in line, providing a crucial vote against a consumer protection measure that brought the Senate to a 50-50 tie, and a tiebreaker by Vice President Mike Pence. For all his valiant words, he’s only given the president another victory.

The senator’s decision not to run for re-election – his only substantial action so far – will do little to stop or slow Trump. In fact, Arizonans may very well replace him with a senator who’ll prove to be even more ready to do the president’s bidding.

In the time he has left, Flake still has the considerable powers of a U.S. senator, powers that extend well beyond simple speechmaking. On his own, or in concert with his colleagues, he could still do a great deal to hold the president accountable. He simply needs to find the courage to put his conviction into action.