A couple of days ago President Obama made an appropriate refinement to how he describes the discriminatory and xenophobic tendencies that have become all too obvious in debate and posturing in the United States on issues related to Syria, ISIS, the Paris attacks, and refugees. A week earlier at a press conference in Turkey, in expressing dismay at how “those who have taken on leadership” in the party of George W. Bush ignore how Mr. Bush had made clear that counterterrorism was not a war on Islam, Mr. Obama said, “That's not who we are.” This past weekend, in remarks in Malaysia, the president said that some of the excuses being made for Americans to reject Syrian refugees are “not representative of the best of who we are.” Inclusion of the qualifier the best is important. Although American history has featured the concept of the melting pot and the idea of a new people being created and enriched by the inclusion of diverse other peoples without regard to ethnicity or religion, the United States also has had an ignoble strain of bias and nativism.

That strain has repeatedly surfaced throughout the nation's history, stimulated at different times by different fears and issues. Sometimes such prejudice has been targeted narrowly at some groups and in favor of others—which, in a sense, is the only kind of racial or ethnic bias one should be able to find in a nation of immigrants. This is true of the “Cubans si, Syrians no” approach to the admission of refugees that has become a sore point for certain presidential candidates who have been challenged about it. But underlying the specific manifestations has been a primitive, fearful way of looking at one's circumstances and at the world that says much more about the looker than about the target of the bias. It is a state of mind that involves prejudice against everyone not entirely like oneself. It is a state of mind that Mel Brooks satirized four decades ago in Blazing Saddles.

One of the most politically significant past manifestations of the nativist strain was the Know-Nothing Party (officially, the American Party), which enjoyed some electoral success in the 1850s. The Know-Nothing platform centered around opposition to immigrants and especially to Catholic immigrants from Ireland and Germany (although the party sought the support of native-born Catholics in the South). The party reached the peak of its strength in 1854, when it won 52 seats in the U.S. House of Representatives (more than one-fifth of the chamber) and won control of several large northern cities and the Massachusetts legislature. In the presidential election of 1856 the Know-Nothing ticket (led by former president Millard Fillmore, who did not seek the nomination) won 22 percent of the popular vote nationwide and carried the state of Maryland.

Later upsurges of nativism were mixed with other forms of bias, such as in the heyday of the Ku Klux Klan in the 1920s. Repeatedly there has been a reluctance to welcome foreign refugees, including Jews fleeing Nazism in Europe in the 1930s and 1940s, despite America being a nation of immigrants. Fear of terrorism also has gotten mixed into issues of immigration, as when activity of Lebanese Hezbollah in South America led to imaginary scenarios of terrorists wading into the United States across the Rio Grande.

Now fear of terrorism is again getting infused into issues of immigration and asylum for refugees. Such infusion has little or no merit. It is questionable whether it has merit even in Europe, where the attacks in Paris, accompanied by reports of some of the perpetrators having gotten into the flow of refugees from the Middle East, have fed similar fears on that side of the Atlantic. All of the attackers identified so far are nationals of European Union countries, and the reports of infiltration of refugee flows may be false.

Even assuming the worst as it applies to Europe, the situation in the United States is far different from that in Europe, with its huge numbers of refugees walking across the Balkans and some of them squeezing through border fences. Any sophisticated and reasonably well-heeled terrorist group would be stupid to rely on a U.S. refugee program to move operatives into the United States, given the very time-consuming and detailed vetting process involved. It would be quicker and easier to do so with tourist or business visas, as the 9/11 hijackers did.

The refugee asylum issue is being treated as it is in U.S. political debate because of the same sort of nativist inclinations that have repeatedly surfaced in the past. One indication of this is how big a role anti-immigrant themes had played in the contest for the Republican presidential nomination even before the events in Paris.

The Republican campaign also demonstrates how much the whole set of attitudes involved has become another of the multitude of issues and attitudes in this country that demonstrate a marked partisan split. The split is not total and clean, and it never has been with American nativism. The mayor of Roanoke, Virginia who approvingly referred to the internment of Japanese Americans (whom he mistakenly described as “Japanese foreign nationals") during World War II is a Democrat. And 47 of the 188 Democrats in the House of Representatives voted in favor of the recent bill that would curtail even the current small numbers of grants of asylum to Syrian refugees. But Republican support in the House for the same bill was a near-unanimous 242 votes. The leading Republican candidate for the presidential nomination has indicated he would support establishment of a registry of Muslim Americans, although he later maybe backed off a bit, blaming loud music for the way he had answered a question on that subject. His opponents for the nomination have tried to match his appeal to the sentiments involved by advancing ideas such as that only Christians and not Muslims should be admitted as refugees from deadly turmoil in the Middle East.

Islamophobia has been the dominant sub-thread in the most recent manifestation of the longstanding nativist, prejudicial thread in American attitudes. It too, demonstrates a marked partisan difference. Given the way Americans take many of their cues from leaders of whichever party they identify with, it is hard to say which came first, the demos or the demagogue. What can be said is that themes along this line in the Republican primary campaign are appeals to attitudes that opinion polling confirms exist in the party base. In a recent Bloomberg poll, a large majority of Republicans, 69 percent, versus only 36 percent of Democrats, opposed admitting any Syrian refugees to the United States. This finding is very likely related to attitudes uncovered by the question that the pollsters asked immediately before that and gets closer to tapping Islamophobia. Nearly twice as many Republicans as Democrats (32 percent to 17 percent), believed that “Islam is an inherently violent religion, which leads its followers to violent acts” rather than being a peaceful religion with “some who twist its teachings to justify violence.” There are respectable ways to debate related questions about a religion that expanded in large part by the sword, but it is a safe bet that the answers of the vast majority of respondents in this poll were not based on a study of Islamic history or exegesis of the Koran.

The rise and decline of the Know-Nothings occurred in a period of much flux in the American party system. The Know-Nothings benefited from the decline of the Whig Party. But then they themselves were hurt by the same intense divisions over slavery that helped to disable the Whigs. A new party, the Republican Party, emerged and quickly ascended by being clearly and firmly on the right side of the slavery issue.

The Republican Party has performed a great reversal with regard to issues of inclusiveness or exclusiveness and the attitudes to be applied to those with characteristics or backgrounds different from one's own. From the inclusiveness of the anti-slavery cause, it now has come to fill the role of the Know-Nothings. Unlike the Know-Nothings, it is not going away. There is no current issue comparable to slavery that has the same capacity to reshuffle the party system. And by amalgamating an issue such as immigration or asylum for refugees with issues of terrorism and security, it can present at least a verisimilitude of consistency and of having worthy reasons for its candidates to appeal to sentiments that represent not the best of who we are but rather something else.