LONDON >> A day after Republican candidate Donald J. Trump called for a ban on the entry of Muslims into the United States, much of the rest of the world looked at the American presidential election on Tuesday with a mix of befuddlement and despair, wondering how the same nation that twice put the black son of a Muslim from Kenya in the White House could now be flirting with Trump and his divisive, exclusionary stances.

Trump’s position had its admirers. His stance on Muslim immigration drew several hundred favorable comments on China’s Twitter-like social media site, Weibo, where supporters linked his idea to their own fears of the Uighurs, a minority Muslim group in China’s northwestern region whose violent militancy has become a major concern.

But in many other places, it ignited widespread condemnation that crossed ideological and social lines.

In Britain, Prime Minister David Cameron, of the Conservative Party, called his words “divisive, unhelpful and quite simply wrong.”

Prime Minister Manuel Valls of France, which is still reeling from deadly attacks by Islamic extremists, wrote on Twitter: “Mr. Trump, like others, fuels hatred,” and “Our only enemy is radical Islamism.”

Trump’s comments were widely shared on social media throughout the Arab world. In a region racked by conflict, his language had an impact, including in Egypt, where he was condemned by the country’s highest religious authority and by many others, who called him an Islamophobe, a racist or, as Reem Khorshid, a 21-year-old engineering student and blogger, put it, “a madman who has no sense at all.”

Rachid Tlemcani, a professor of political science at the University of Algiers, warned that Trump threatened to push young people toward the Islamic State.

“A lot of people in the Middle East think of the United States as the last place we can go if things turn really bad, as it is the place of freedom and liberty,” Tlemcani said. “I think that sort of comment could even invite some act of violence against America. I think he is not responsible.”

The type of attention being paid to Trump stands in sharp contrast to the last time a presidential election in the United States riveted the world — in 2008, when Barack Obama’s candidacy was widely embraced in other nations eager for what they viewed as a revival of American ideals. During that campaign, Obama was greeted by more than 200,000 people in Berlin, and his victory was widely hailed as an affirmation of the best of America.

As in the United States, Trump has incited particularly intense debate, not least in predominantly Muslim countries and in Europe, where far-right parties like Marine Le Pen’s National Front have been gaining ground by invoking anti-immigrant messages similar to those of Trump and where memories of 20th-century fascism run deep.

J.K. Rowling, the British author of the best-selling Harry Potter books, even mused that Trump was worse than the books’ archvillain, Lord Voldemort.

Charles Grant, the director of the London-based Center for European Reform, said Trump was anathema to many Europeans because his populism had edged toward fascism and conveyed a willingness to preach an open hatred of religious minorities that many far-right leaders, from Le Pen in France to Nigel Farage of the euroskeptic U.K. Independence Party in Britain, tried to temper as they fought to move their parties into the political mainstream.

Grant added that Trump conveyed an ignorance of world affairs that Europeans found hard to stomach from a contender in a national election in the United States.

“Donald Trump strikes me as a very different kind of populist right-winger than the kind we’ve grown used to in Europe in that he shows a complete ignorance about the world,” Grant said. “While Le Pen and others may say things that are alarmist, they at least acknowledge the premise of religious tolerance we’ve had in Europe since the 18th-century Enlightenment.”

“To many Europeans,” he added, “it is deeply alarming that he is doing so well.”

In France, which is grappling with the challenges of integrating a large Muslim population, the newspaper Le Monde called Trump’s comments “unprecedented.”

But observers in France, where the National Front won the first round of regional elections last weekend, also noted that Trump reflected a familiar nationalist and anti-immigrant impulse, extending from Paris to Budapest. After the recent influx of migrants to Europe, many of them from the Middle East, Prime Minister Viktor Orban of Hungary repeatedly said that his country had a right to protect its Christian traditions by refusing to accept large numbers of Muslims.

In La Défense, a business district west of Paris, Inès Lessieur, 23, a student, said Trump depressed her. “I am sure he’ll get elected,” she said. Another student, Laura Albat, 20, responded, “No, a country that voted twice for Obama cannot elect a man like that.”

Some analysts, however, said that Trump was more recognizable in Europe that most people liked to admit and that his stances resembled those of not just Le Pen but also other larger-than-life politicians who appealed to voters fed up with the staid political mainstream.

“Many Italians think Trump is a sort of American version of Silvio Berlusconi, a big personality without the background of what it means to be a politician,” said Sergio Fabbrini, director of the school of government at Luiss Guido Carli University in Rome. “Both are outsiders with a politically incorrect style, dividing American politics as Italian politics were divided.”

In the Arab world, Trump’s anti-Muslim comments have yielded growing concern, as many watch the American primary campaigns with alarm about what the election could mean for the involvement of the United States in their region.

“There is something disturbing about where the Americans are going in their relations with the outside world in general and with the Arab and Islamic world in particular,” said Abdulkhaliq Abdulla, a retired professor of political science from the United Arab Emirates. “All of a sudden it seems that America, or at least some segments of America, have forgotten what America stands for.”

Hafez Al Mirazi, the director of the Kamal Adham Center for Television and Digital Journalism at the American University in Cairo, contrasted Trump’s comments with the moment in 2009 when Obama spoke in Cairo and attempted to reach out to the Arab and Muslim world, inspiring many with his personal story of success.

“What we are getting now is really terrible,” Mirazi said. “Stuff that only the Ku Klux Klan and others would say.”

Mirazi, who lived in the United States and whose children attended American schools, said he was worried that Trump’s positions could also create a “disenfranchised generation” of Arabs in the United States, who are for the most part better integrated than their counterparts in Europe.

Dar al-Ifta, the authority that issues religious edicts in Egypt, released a statement calling Trump’s comments “extremist” and warned that they “threatened societal peace” in the United States.

“He’s not just a regular guy or some fanatic,” said Ibrahim Negm, a spokesman for the authority. “He would be the president of one of the most powerful countries in the world, that hosts 6 to 8 million American Muslims. This is indeed alarming.”

But in a world in which terrorism has come to be associated with radical Islam, Trump’s stance resonated among people who perceive a similar threat.

“Honestly, I support his ideas,” wrote one user of the Weibo social media service in China. “If this guy could get in the White House, I hope he could do what he said — stop the entry of Muslims.”

Another wrote of Trump, “If he gets elected, the United States will have hope again.”

Shen Dingli, a professor of international relations at Fudan University in Shanghai, said Trump’s mentality of “maximum security” struck a chord with many Chinese, who live in a highly conservative society that is more closed than the United States.

“Actually, the Chinese could be the people who understand Trump the most,” Shen said.

© 2015 The New York Times Company