At the beginning of an event on black leadership, President Trump told the crowd an arrest had been made in the investigation of bombs sent to prominent Democrats and Trump critics.

"I am pleased to inform you that law enforcement has apprehended the suspect and taken him into custody. It's an incredible job by law enforcement," he said, adding that it was a "special day."

Just before Mr. Trump was scheduled to deliver remarks for Turning Point USA's black leadership summit at the White House Friday, law enforcement officials arrested 56-year-old Cesar Sayoc in Florida.

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"These terrorizing acts are despicable and have no place in our country," the president said. We must never allow political violence to take root in America. I'm committed to doing everything in my power to stop it," Mr. Trump vowed.

He also praised U.S. law enforcement for doing "an incredible, incredible job" and called it the "best in the world." And he called on Americans to unify and "show the world we are united in peace and love and harmony."

Mr. Trump, who condemned political acts of violence from the same room earlier this week, had taken a more heated approach on Twitter, blasting the media for how it has covered his response to the saga.

"Funny how lowly rated CNN, and others, can criticize me at will, even blaming me for the current spate of Bombs and ridiculously comparing this to September 11th and the Oklahoma City bombing, yet when I criticize them they go wild and scream, 'it's just not Presidential!'"

In subsequent remarks to the group, Mr. Trump sounded the themes of his campaign, talking about his appeal to African Americans. He reminded the group that when he was running for president, he had asked black Americans to take a chance on him. "'What the hell do you have to lose?' Remember? Remember?" he asked the crowd. African American unemployment has dropped, "the lowest level ever recorded in the history of our country," he declared, to cheers in the room.

Mr. Trump talked about immigration, saying that illegal immigration is harmful to African American and Hispanic workers because their wages are being depressed. And he brought up the caravan of Central Americans making their way north through Mexico to the U.S.

"It's a big caravan," he said. "I called up the military. We're not letting them in." The president said that he welcomes legal immigration, however. "Do we want them to apply and come in legally? Absolutely," he said. "And we also want people to come in on merit."

Mr. Trump mentioned Kanye West during his remarks, whom he called a "smart guy and a good guy." The president claimed that after his meeting with West, his pollsters told him that his approval ratings among African Americans went up 26 points. "Kanye may be the most powerful man in American politics," he said.

Turning Point USA, a conservative nonprofit group focused on educating high school and college-aged students, has become particularly known for sometimes inflammatory comments made by two of its leaders, Charlie Kirk and Candace Owens.

Owens, for instances, was one of a handful of far-right figures who suggested, without evidence, that the explosives were fake and set up by "leftists."

"The only thing 'suspicious' about these packages, is their timing," she said Wednesday in a tweet that has since been deleted. "Caravans, fake bomb threats, leftists are going ALL OUT for midterms."

But Mr. Trump himself suggested the "'bomb stuff" was distracting from the midterms.

"Republicans are doing so well in early voting, and at the polls, and now this "Bomb" stuff happens and the momentum greatly slows - news not talking politics. Very unfortunate, what is going on. Republicans, go out and vote!" the president tweeted Friday morning.