A 20-year-old man has been arrested after being filmed sucker punching a black Trump protester at an America First rally in California.

Richard Losey was filmed attacking Republican activist R.C. Maxwell at the rally in Laguna Beach on Sunday.

Maxwell, an entrepreneur who refers to himself as the black Sean Hannity, was talking to counter protesters when Losey sneaked up behind him and hit him in the head.

Footage of the attack was shared online afterwards and was handed to police. Losey, who identified himself and boasted about the punch on Twitter, was arrested trying to buy a bus ticket to get back to his native Ohio on Tuesday.

He remains in Orange County Jail on a charge of misdemeanor assault with a hate crime enhancement with bond set at $50,000.

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Richard Losey (seen above wearing a baseball hat) was filmed sucker punching black Trump supporter R.C. Maxwell at a protest on Laguna Beach, California, on Sunday

The pair were among 2,500 others who descended on Main Beach for the demonstration on Sunday night.

Maxwell, who is the national coordinator for the Republican PAC American Voice, said he was trying to engage in calm debate with the other side when he was attacked.

'I went over to the left side to see if I could engage them with dialogue and I was instantly encircled by the so called anti fascists,' he told Fox News.

Footage shows him standing in front of the crowd, speaking animatedly, when Losey approached him slowly from behind.

He suddenly raised his hand to strike Maxwell on the head then brought him to the ground as onlookers scuffled and gasped.

Unrepentant, Losey identified himself on Twitter on Tuesday after footage of the incident surfaced online.

Maxwell, who calls himself the black Sean Hannity, said he was attacked because of the color of his skin. Losey, 20, remains in Orange County Jail on a $50,000 bond for assault with a hate crime enhancement

Losey boasted about the attack on Twitter, saying Maxwell 'had it coming' but insisting he was 'not racist'

Losey was arrested on Tuesday in California trying to buy a bus ticket back to his native Ohio. He remains in county jail

In a string of tweets posted hours before he was arrested trying to make his way back to Ohio, he claimed not to belong to any political group and denied being racist, as had been suggested by Republicans, but said Maxwell 'had it coming'.

'I'm the dude who fought him haha [sic] I AM NOT APART IF A GROUP I did what I had to do, we didn't want him there and he didn't leave.

'I did what I had to do. He ran and left us alone when his input wasn't wanted. We all told him to leave and he didn't. He had it coming.

'I did it because he would stop talking about Trump when all of us told him thousands of times we didn't want to hear it. I am NOT racist,' he said.

Maxwell maintains that he is singled out by liberals who are uncomfortable with his position as a black Trump supporter

In one post he taunted: 'Please arrest me lmao'. It is not clear why he had traveled to California.

The California native said it is his goal to educate black voters and persuade them to align with the president

Losey describes himself as a crewman at an Ohio-based granite company on social media.

Maxwell is a keen Trump campaigner whose self-proclaimed mission is to educate black voters and persuade them to align with the president and his agenda.

Among his political views, which he characterizes as politically incorrect, is that removing Confederate statues will be inconsequential to the racial inequality.

He believes he was attacked at the Laguna Beach rally because he is black.

'I'm okay always attacked at these things because liberals hate the rising number of young minority conservatives.

'It really hurts their narrative that Republicans are Nazi's.

'Don't worry the alt left will have to try harder than this to silence me,' he said in a Facebook post after the attack.