WASHINGTON (AP) — U.S. Sen. Mitt Romney marched Sunday in the nation's capital in a protest against police mistreatment of minorities, making him the first Republican senator known to do so.

Romney, who represents Utah, posted a tweet showing him wearing a mask as he walked with Black Lives Matter protesters in Washington. Above the photo he wrote: Black Lives Matter.

Romney, who was walking with a Christian group, told NBC News that he needed to be there.

"We need a voice against racism, we need many voices against racism and against brutality," he said. "We need to stand up and say, 'Black lives matter.' "

On Saturday, Romney tweeted a photo of his father, George, who was the governor of Michigan from 1963 to 1969, marching with civil rights protesters in the 1960s in a Detroit suburb.

Above the photo, Mitt Romney wrote: "This is my father, George Romney, participating in a Civil Rights march in the Detroit suburbs during the late 1960s — "Force alone will not eliminate riots," he said. "We must eliminate the problems from which they stem."

Romney also wrote two other tweets on May 30 and May 28 criticizing the Minneapolis officers involved in the death of George Floyd.

The May 30 tweet said: "The George Floyd murder is abhorrent. Peaceful protests underscore the urgency of addressing injustices. But violence drowns the message of the protestors and mocks the principles of justice."

The May 28 tweet said: "No Americans should fear enmity and harm from those sworn to protect us. The death of George Floyd must not be in vain: Our shock and outrage must grow into collective determination to extinguish forever such racist abuse."

Romney has been one of the more independent members of the U.S. Senate's GOP caucus. He voted to remove President Donald Trump from office after the impeachment trial.