Roberto Beristain, a 43-year-old undocumented immigrant, had lived in the United States for nearly 20 years. He and his wife of 17 years, Helen, an American, were raising their four children in St. Joseph’s County, Ind., and he owned a beloved local institution, Eddie’s Steak Shed.

Late Tuesday night, Mr. Beristain, whose wife voted for President Trump, was deported and dropped off in Juárez, Mexico, by Immigration and Customs Enforcement officials.

“It feels like a defeat for our community,” Pete Buttigieg, the mayor of South Bend, Ind., in St. Joseph County, said on Friday. “Here we have someone who was trying to do everything right, who has kids — who are totally American and part of this community — who no longer have their father.”

“There’s no path to citizenship,” Mr. Buttigieg, a Democrat, said. “There are a lot of conservatives who do believe there should be a path to citizenship for somebody like him. The reality is the bureaucracy has let him down.”

Mr. Beristain had twice filed a green card application and had a Social Security card, a work permit and a driver’s license, according to Mr. Buttigieg and Adam Ansari, a Chicago lawyer and former neighbor of the Beristains who used to frequent Mr. Beristain’s restaurant.

“We’ve got to come up with something,” Mr. Buttigieg said. “Some answer other than, ‘Get out.’ ”

Customs enforcement did not immediately comment on Friday.

Only a couple of months into his presidency, Mr. Trump has emboldened immigration agents to deport undocumented individuals, encouraging agents to shed the practice of focusing mostly on those with criminal records. Mr. Beristain has no criminal record, Mr. Ansari has said.

On Feb. 6, Mr. Beristain was detained during his regular yearly hearing with immigration officials. Between that day and his deportation, he was moved by immigration agents through centers in Indiana, Wisconsin, Illinois, Louisiana, New Mexico and Texas, Mr. Ansari said.

Mr. Beristain is not alone in this experience. In February, for example, residents in an Illinois town were shocked when a manager of a popular restaurant was arrested by immigration agents.

Last month, Mr. Buttigieg wrote in The Huffington Post about why Mr. Berstain’s community, considered to be a conservative area, was largely sticking up for “an undocumented neighbor.” In it, he wrote that supporting Mr. Beristain is in line with his community’s values: “hard work, small business ownership, suspicion of overbearing government and support for family.”

In the November election, St. Joseph County — which includes Mishawaka, where the Beristains live — was split nearly evenly between Mr. Trump and his Democratic opponent, Hillary Clinton. But Mr. Buttigieg says that Mr. Beristain’s deportation has affected some Republican residents’ opinions of the president.

“I got one letter from somebody who knows the family personally who’s also a Trump supporter basically saying, ‘Look, this isn’t what we thought we were voting for,’ ” Mr. Buttigieg said. “But then again, political habits die hard.”

The reactions have not all been supportive. The mayor said that the Beristains’ eighth- and ninth-grade daughters were on “the receiving end of some ugliness at their school.” He added that there had been some negative responses from people online, who have said that Mr. Beristain does not have an excuse because he had years to try and become a citizen.

The mayor said it was important to view the story as a human one, not just a political one. “That’s equally applicable to people in the anti-Trump world who are saying that somehow this family deserve it,” he said. “I think this is a moment where compassion has to come first.”

Mr. Ansari — who has been helping the family and has assembled a team of immigration lawyers to provide them counsel — said the deportation was unlawful and a surprise because the lawyers had several pending motions on behalf of Mr. Beristain, which were being relayed to immigration officials.

“Unbeknownst to us, during the same exact time we were talking to immigration officials, they were shuffling him off to Mexico,” Mr. Ansari said on Thursday, adding that the lawyers were not aware that Mr. Beristain had been taken to Mexico until they received a call from Ms. Beristain. She received no information from immigration officials, Mr. Ansari said.

In an interview in March, Ms. Beristain told a CBS affiliate in South Bend, Ind., “I don’t think ICE is out there to detain anyone and break families, no.”

Referring to Mr. Trump, she added, “Like he said, the good people have a chance to become citizens of the United States.”

The New York Times was unable to reach Ms. Beristain for comment on Friday.

Mr. Buttigieg is still hoping for some kind of compromise solution.

“My hope is that there might be kind of a redemption in the idea that we all want there to be some kind of way for someone in this position to pay a penalty, get in line and get right with the law, he said. “That’s really all they’re asking for.”