When they shouted, "Black lives matter!" a rallying cry of protests that broke out after several black Americans were killed at the hands of police in recent months, O'Malley responded: "Black lives matter. White lives matter. All lives matter."
Invoking the familiar names of blacks who died at the hands of police, including Eric Garner, Michael Brown and Tamir Rice, thousands have taken part in protests across the country calling for a more aggressive federal response to recent slayings by police. A protester is arrested at the demonstration on December 13 in Oakland.
The demonstrators, who were mostly black, responded by booing him and shouting him down.
Later that day, O'Malley apologized for using the phrase in that context if it was perceived that he was minimizing the importance of blacks killed by police.
"I meant no disrespect," O'Malley said in an interview on This Week in Blackness, a digital show. "That was a mistake on my part and I meant no disrespect. I did not mean to be insensitive in any way or communicate that I did not understand the tremendous passion, commitment and feeling and depth of feeling that all of us should be attaching to this issue."