Ekram Elmoge, a 21-year-old who resettled in St. Cloud from Somalia about five years ago, described the city as “diversity without inclusion.” Ms. Elmoge said she had been harassed by white residents, who have yelled, “Go back to your country” and “You’re here for free money.” She is currently enrolled at St. Cloud State University, where Mr. Palmer used to be a professor.

“It’s hard to be accepted for who you are,” Ms. Elmoge said. “The people here who have accepted me have been white. But the people who have not accepted me are also white. They say ‘go back to your country’ and ‘you make St. Cloud a bad place to live.’”

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In interviews, the C-Cubed members and allies remain undeterred, and they are setting their sights on helping Republicans make gains in the 2020 election. At one of the group’s events last year, some residents donned hats that read “Make St. Cloud Great Again” for a “Red Hat forum,” where local law enforcement officers and national anti-Muslim speakers were invited. Similar speakers have been invited to a local church, Granite City Baptist, a mostly white congregation on the city’s west side.

During a meeting of about 10 C-Cubed members in April at the Faith Lutheran Church in St. Cloud, Mr. Palmer steered a free-flowing discussion that began by comparing abortion access to the Holocaust and moved on to the city’s so-called refugee problem, and what the group could do to address it. Almost all of those present voiced some support for Mr. Trump. Others said that markers of progress were more interpersonal, and they would only be comfortable in their community if the Somali-born refugees converted to Christianity.

One woman, who declined to give her name after the group discussion, bemoaned the city’s so-called no-go zones, or the areas where white residents said they felt so uncomfortable with the Somali-American presence that they would not return — a shopping mall, a community housing center and Beaver Island Trail, a hiking area that borders the Mississippi River.

“They were just —” she said, searching for the words to describe the offending behavior of the Somali-Americans. “They were just walking around.”