"He put down the phone and says, 'Come on in, boys,' " Romero says. "You could tell when he was looking at you, that he's not looking through you — he's taking you into account. And I remember walking out of there like I was 10 feet tall."
The next day, Kennedy defeated Sen. Eugene McCarthy to win the Democratic primary. After giving his victory speech in the ballroom, Kennedy was led through the kitchen on his way to meet the press and he stopped to shake hands with some of the staff along the way.
"I remember extending my hand as far as I could, and then I remember him shaking my hand," Romero says. "And as he let go, somebody shot him."
His next actions are now immortalized in photos taken by journalists there for the victory speech.
"I kneeled down to him and I could see his lips moving, so I put my ear next to his lips and I heard him say, 'Is everybody OK?' I said, 'Yes, everybody's OK.' I put my hand between the cold concrete and his head just to make him comfortable."
"I could feel a steady stream of blood coming through my fingers," Romero says. "I remember I had a rosary in my shirt pocket and I took it out, thinking that he would need it a lot more than me. I wrapped it around his right hand and then they wheeled him away."
Romero, then 17, rode the bus to high school the following day. He tried not to think about the shooting, he says, but a woman sitting nearby had been reading the newspaper plastered with the scene.
"She turned around and showed me the picture," Romero says. "She says, 'This is you, isn't it?' And I remember looking at my hands and there was dried blood in between my nails."
Then, letters addressed to "the busboy" flooded in to the Ambassador Hotel.
"There was a couple of angry letters," he remembers. "One of them even went as far as to say that, 'If he hadn't stopped to shake your hand, the senator would have been alive,' so I should be ashamed of myself for being so selfish."
Romero says it has been "a long 50 years," and he still gets emotional about his role that night. In 2010, he says he paid a visit to RFK's grave in Arlington National Cemetery in Virginia.
"I felt like I needed to ask Kennedy to forgive me for not being able to stop those bullets from harming him," he says.
As a sign of respect, he says, he bought his first-ever suit for the occasion.
"When I wore the suit and I stood in front of his grave, I felt a little bit like that first day that I met him. I felt important. I felt American. And I felt good."
Audio produced for Morning Edition by Jud Esty-Kendall