Fox News personality Geraldo Rivera is calling on Republican presidential candidate Donald Trump to take back what he said about many Mexican immigrants being "rapists."

Rivera is also the runner-up of the latest season of NBC's "Celebrity Apprentice," which is hosted by Trump.

"To Donald Trump from a friend for life and admirer," Rivera wrote in a Twitter message to Trump on Sunday. "Please apologize for crude generalization of 11 million undocumented [immigrants]. It hurt many good people."

When he announced his campaign for the White House two weeks ago, Trump railed against U.S. immigration policy. "The U.S. has become a dumping ground for everybody else's problems," he had said. "When Mexico sends its people, they're not sending their best. They're sending people that have lots of problems, and they're bringing those problems with [them]. They're bringing drugs. They're bringing crime. They're rapists. And some, I assume, are good people."

Those remarks prompted Spanish-language channel Univision to cut ties with Trump's "Miss Universe" pageant. Trump said he would sue the channel for breach of contract.

In an interview on CNN Sunday, Trump did not back down from his remark about Mexicans. "You have people coming in, and I'm not just saying Mexicans," he said. "I'm talking about people that are from all over that are killers and rapists, and they're coming into this country."

Reliable numbers on illegal immigrants and crime are difficult to find. But a 2014 Pew Research study found that of the illegal immigrants who were deported in 2013, "33 percent had committed at least one felony — crimes ranging from murder to failure to appear in court, or at least three misdemeanors."