Alabama Sen. Doug Jones on Monday became the latest Democrat to criticize President Trump for not condemning white nationalism more forcefully after a man who killed 50 people in a mass shooting at a New Zealand mosque last week published a racist manifesto that mentioned Mr. Trump. Once the killer's manifesto came out, the president "should have made a stronger stand: 'That's not what I'm about. That's not who I am. That's not what my political leanings are,' and made a very, very strong stand," Jones told CBSN's Elaine Quijano on "Red & Blue."

"I worry sometimes that the president is so concerned about losing some of his base that are that very far right — that's just a fact — that he won't take those necessary steps."

Mr. Trump had expressed sympathy for the victims of the attack, but when asked by a reporter Friday whether he believed "that white nationalism is a rising threat around the world," he responded, "I don't really. I think it's a small group of people that have very, very serious problems, I guess."

Get Breaking News Delivered to Your Inbox

The president added, "If you look at what happened in New Zealand, perhaps that's the case, I don't know enough about it yet. They're just learning about the person and the people involved. But it's certainly a terrible thing."

Jones, who has just written a book chronicling his prosecution of two white supremacists, "Bending Toward Justice: The Birmingham Church Bombing that Changed the Course of Civil Rights," thinks there's "no question" that white nationalism is on the rise. "I think clearly what you see around the country today," he said. "It's on the rise and it's a little scary I think for folks. It should be a little bit scary."

"White nationalism was more of a — just nationalism," Jones said. "And it has evolved into more of a race issue because we do see America becoming more diverse every day. And that bothers people. It scares some people. They have jobs. They have families, and they're just not used to this. And fear is an incredibly motivating factor sometimes, and that's what social media does for these trolls. They play on that fear, and people let it get the best of them."