As protests over police brutality rage across the nation, President Trump predictably responded with a call for an aggressive response against rioters.

“Get tough Democrat Mayors and Governors,” he tweeted Sunday. “These people are ANARCHISTS. Call in our National Guard NOW.” On Monday, he held a conference call with the nation’s governors, urging them to seek “retribution” against rioters he characterized as “scum” and “terrorists.” “You have to dominate or you’ll look like a bunch of jerks,” he told the governors; “you have to arrest and try people.” His approach was summed up in a simple all-caps tweet: “LAW & ORDER!”

The president’s theme is a familiar one for him. During the 2016 campaign, he insisted that “I am the law and order candidate,” and during his inaugural address he promised that “this American carnage stops right here and right now.”

Now his aides reportedly believe the approach will work well for his reelection campaign, staged against a drumbeat of demonstrations and uprisings. “Some in the president’s circle see the escalations as a political boon,” the New York Times reported Monday, “much in the way Richard M. Nixon won the presidency on a law-and-order platform after the 1968 riots.”

While the future of American politics is impossible to predict, that statement reveals a serious misreading of the past. This year, Trump may try to replicate the rhetoric of his predecessor’s campaign, but there’s one important aspect he can’t copy — the fact that Nixon, unlike Trump, wasn’t president when he waged it.

To be sure, Nixon did rely heavily on the theme of “law and order” as the Republican presidential candidate in 1968.

Over the previous decade, the nation had been rocked by political assassinations, urban uprisings, rising crime rates and Supreme Court rulings extending new rights to criminal defendants. Kevin Phillips, a Republican strategist, asserted in a campaign memo that Nixon “should continue to emphasize crime, decentralization of federal social programming, and law and order” to win over white voters.

At the GOP convention that August, the nominee pledged he would “restore order and respect for law in this country” as president. “The wave of crime is not going to be the wave of the future in the United States of America.”

This theme defined the campaign. “By every sign and portent,” one veteran journalist noted that summer, “Nixon will accentuate the ‘law and order’ issue.” He spoke often about it on the campaign trail and even devoted a memorable minute-long television ad to the topic. Images of violent protesters and armed police officers flashed across the screen, a discordant montage set to jarring music, followed by Nixon’s solemn promise: “I pledge to you: We shall have order in the United States.”

It worked, largely by winning over disaffected Democrats, most notably white Southerners and white ethnics from Northern cities. Peeling away those white Democrats, Phillips argued, would be the key to winning in 1968 and creating a lasting political realignment that would usher in what he called “the emerging Republican majority.” And the “fulcrum of realignment,” he argued in a campaign strategy memo, “is the law and order/Negro socioeconomic syndrome.”

Newspapers tracked its effectiveness. “It’s well documented by now that law and order is the No. 1 domestic issue of this election,” the Wall Street Journal reported in late October 1968. “Countless voters across the land, even in places lacking muggers and rioters, are gripped by fear for their safety.” Polls asking which candidate could “maintain law and order” gave Nixon a 12-point lead. Thanks to that commanding margin on a key issue, Nixon secured a narrow victory in November.

The message worked, but only because Nixon was the outsider running against the incumbent vice president, not the sitting president. The call for “law and order” is a complaint that those tasked with upholding the law and maintaining order have failed at the job and need to be replaced.

In 1968, Nixon’s law-and-order campaign rested on his repeated claims that Lyndon B. Johnson’s administration was largely to blame for the nation’s lawlessness and that only replacing it with a new administration would solve them. “If we are to restore order and respect for law in this country,” Nixon vowed in his acceptance speech, “there is one place we are going to begin. We are going to have a new attorney general of the United States of America.”

As a presidential candidate, Nixon was able to run, and win, on a critique of the status quo. But once he was president, that critique no longer worked.

Nixon learned this the hard way in the 1970 midterm elections. He spent the fall campaigning across the country for GOP candidates, with the “law and order” message front and center. “From Missouri to Tennessee to North Carolina and Indiana,” a reporter noted in late October, “he urged more respect for police, plugged the virtues of Republican congressional candidates and asked ‘the silent majority of America to stand up and be counted against violence and lawlessness.’ ” The president urged Americans “in the quiet of the polling booth” to vote for Republicans and thereby strike a blow against politicians who “condoned lawlessness and violence and permissiveness.”

This time, the appeal fell flat. Republicans lost 10 seats in the House and, more significantly, lost a large number of governor’s races across the country, including almost all the Midwest. The Los Angeles Times captured the rebuke well in a headline: “Silent Majority Speaks Out, Rejects Law-And-Order Alarm, Votes Liberal.”

An astute politician, Nixon learned the lesson immediately. “The White House has already begun a campaign to alter President Nixon’s image in preparation for the 1972 elections,” the Boston Globe reported just a week after the midterm defeat. “Law and order, the principal issue of the disappointing 1970 campaign, will be soft-pedaled.”

Sure enough, it was. While the 1968 campaign had featured a fearmongering ad on the theme of “law and order,” the 1972 reelection effort was characterized by an upbeat commercial filled with beachgoers and butterflies.

As the campaign drew to a close, politicians and political observers alike marveled at how the “law and order” theme had evaporated. The incumbent Nixon had realized he couldn’t use it, while Democrats — who saw the phrase as inherently racist — refused to use it against him.

As a result, the issue faded away, with Republican Sen. Jack Miller of Iowa observing how the issue “has certainly gone on the back burner.”

Nixon won a landslide reelection that year, of course, but not because of any concerted appeal to the “law and order” crowd. Rather than highlight divisions and court controversy, the incumbent president emphasized the changes he had made in foreign policy and his promise to end the war in Vietnam, as well as an assortment of other domestic issues.

As a presidential candidate, Nixon manipulated the issue of “law and order” for his own ends. But as president, he learned it was a losing issue for the politician then in charge.

The call for “law and order” is, at heart, a call for a new order, a call for the current leadership to be replaced. An incumbent who presses the issue is effectively making the case for his opponent, not himself.