One of the most respected civil rights activists in the country has joined a growing number of people who have vowed to publicly boycott the San Francisco Giants.

Dr. Harry Edwards announced Sunday he is supporting Oakland-based civil rights attorney John Burris in calling for a “total boycott” of the Giants after public election filings revealed one of the team’s owners, Charles B. Johnson, donated the maximum $2,700 to the campaign of Cindy Hyde-Smith, a Republican U.S. Senator from Mississippi who has expressed racist sentiments.

Hyde-Smith is facing Democrat Mike Espy in a runoff Tuesday for the final undecided Senate seat in the 2018 midterm elections and has made numerous controversial remarks during her campaign. On November 11, a video from a campaign rally revealed Hyde-Smith saying she would “be on the front row” if invited to a public hanging.

Edwards tweeted that he will boycott all Giants games, community events and other activities “until its owner explains his financial support for segregationist advocates of public hangings and ‘monkey’ comments.”

In a letter made public through Edwards’ tweet, Burris wrote that “it is anathema to my sense of social justice to support a team whose owner financially supports Hyde-Smith.”

Johnson’s donation to Hyde-Smith’s campaign was made about a month after election filings showed he donated $1,000 to a super PAC called Black Americans for the President’s Agenda that aired racist advertisements in Arkansas supporting Republican incumbent Congressman French Hill.

Johnson issued a rare statement denouncing the super PAC’s actions and condemning racism, but neither Johnson or any other members of the organization have commented publicly on his donation to Hyde-Smith’s campaign.

A photo from Hyde-Smith’s Facebook page showed her with confederate items and a caption, “Mississippi History at its best!” According to reports from Jackson Free Press, Hyde-Smith also attended Lawrence County Academy, a high school created for parents who did not want to send their children to school with black students.

Major League Baseball also donated $5,000 to Hyde-Smith’s campaign nearly three weeks after her comments regarding a public hanging, but the league asked Hyde-Smith to return to the contribution. MLB spokesman Pat Courtney said the donation “was made in connection with an event that MLB lobbyists were asked to attend.”

Johnson’s donations have outraged many Giants fans who have pledged on social media to stop spending money on tickets and merchandise until Johnson sells his stake in the team. Johnson is believed to hold the largest stake of the Giants, but the team website lists him among 28 other principal owners.

Edwards is a professor emeritus of sociology at UC Berkeley, has served as a consultant to both the San Francisco 49ers and Golden State Warriors and is credited as one of the driving forces behind Tommie Smith and John Carlos’ black power salute at the 1968 Olympics.

Johnson, 85, is a retired billionaire residing in Palm Beach, Florida with an extended history of donating to conservative political candidates.