The Trump administration has pulled back its aggressive operations in cities like Chicago and Minneapolis after bad polling indicated the crackdown on illegal immigration was unpopular.

In its wake, however, a new approach is emerging on legal immigration, one that makes it harder for those abroad to enter the United States, and for those already here on a temporary basis to stay. In recent months, Trump administration officials have discussed the legal immigration system as rife with fraud and abuse, and in need of wholesale reform.

The increasingly tough tack on legal immigration was underscored Friday when the Department of Homeland Security announced a policy requiring most immigrants seeking green cards to leave the United States while they wait long periods of time for their applications to be processed.

Green cards are granted to legal permanent residents who have been vetted by the government and are one step away from becoming citizens. The policy caused immigration attorneys to scramble to understand the scope of a process that had long avoided being targeted.

The announcement followed a broader effort to restrict travel for immigrants from more than 35 countries. The Trump administration paused a lottery program that offered more than 50,000 visas internationally. It halted long-term immigrant visas from 75 countries. And it froze immigration applications for those already in the United States from countries on a restricted travel list, making it harder for those nationals to obtain temporary or long-term ways to stay in the country.

The New York Times previously reported that the Trump administration was working on a policy to make it harder for those who could need public assistance to gain a green card.

“They do not see their legal immigration agenda as being separate and apart from their illegal immigration agenda,” said David J. Bier, the director of immigration studies at the CATO Institute, a libertarian think tank. Mr. Bier, who has written about the benefits of immigration, added: “The legal immigration agenda is an extension of their illegal immigration agenda.”

White House officials said that Mr. Trump was focused on helping Americans, and that his travel ban was intended to block immigration from areas with unstable governments.

“It also includes ensuring Americans have access to good-paying jobs at home, and also stopping aliens from exploiting and abusing our immigration system,” said Abigail Jackson, a White House spokeswoman. “This is the common-sense agenda that the American people elected him to enact.”

Mr. Trump has historically spoken positively of legal routes to the United States.

In his State of the Union address in 2019, he declared his support for legal immigration. “Legal immigrants enrich our nation and strengthen our society in countless ways,” he said. “I want people to come into our country in the largest numbers ever. But they have to come in legally.”

It was a version of a refrain he has repeated while directing his administration to block illegal crossers at the border and mass deport those in the country illegally: The country needs immigrants who arrive legally, especially those who work in specific jobs and have skills needed for large industries.

Mr. Trump’s comments are in line with the long-held American embrace of legal immigration, often considered a key element of U.S. society that entices skilled immigrants to boost American industries and fill the country’s universities. At one point during the 2024 presidential campaign, Mr. Trump even mused that he would like to give green cards to immigrants who graduate from U.S. colleges, a more expansive benefit than what currently exists.

“I think you should get automatically, as part of your diploma, a green card to be able to stay in this country, and that includes junior colleges,” Mr. Trump told the hosts of a popular tech podcast in 2024.

Mr. Trump has typically directed his disdain toward those in the country illegally, and immigrants who cross the border without authorization. His administration has targeted those in the country illegally for deportation, and has suspended asylum protections for those who enter the country without prior authorization.

But the decision Friday to force immigrants to go abroad to await their green card application decisions — potentially separating families, as spouses are forced to wait — clarified the administration’s new push.

“The focus on ‘illegal’ immigration was a lie meant to distract from their true goal of reducing immigration of all kinds, and we are now watching that vision become reality,” said Amanda Baran, a former Biden administration D.H.S. official who worked on legal immigration matters.

Mr. Trump pulled back immigration agents from Minneapolis after polling showed that Americans were growing disillusioned with his administration’s tactics following the deaths of two American citizens protesting the federal immigration crackdown.

It is unclear whether the administration’s clampdown on legal immigration could have harmful political consequences. But recent polling indicates that Americans are supportive of legal immigration.

“Polling shows Americans support legal immigration in a general, amorphous kind of way,” said Mark Krikorian, the head of the Center for Immigration Studies, an organization that backs tougher immigration policies. But, he added, the system is so flawed that Americans would not object to efforts to fix loopholes and root out fraud.

An Associated Press and NORC poll from last September found that nearly 60 percent of Americans believed that legal immigrants were a major benefit to the economy, and about half believed that they were bringing specialized skills to U.S. companies.