SAN FRANCISCO — A civil rights attorney is calling for a boycott of the San Francisco Giants after the baseball team's principal owner, Charles Johnson, made donations to the campaign of a controversial candidate for the U.S. Senate.

Republican Sen. Cindy Hyde-Smith, who is white, faces Democrat Mike Espy, who would be the first black U.S. senator from Mississippi since Reconstruction. Tuesday's runoff is being held because no candidate reached 50 percent in the first vote on Nov. 6. Hyde-Smith's campaign has been plagued by controversies that evoked Mississippi's history of racism and violence against African-Americans.

"I would encourage everyone who has social consciousness about the conditions that exists in this country should boycott the Giants as long as this person is a principal owner," John Burris, an Oakland-based civil rights attorney, told CBS station KPIX on Sunday.

Video surfaced on Twitter earlier this month showing her praising a supporter by saying, "If he invited me to a public hanging, I'd be on the front row." Hyde-Smith and her campaign initially dismissed the comment as a bad joke but later apologized "to anyone who was offended."

"If he invited me to a public hanging, I'd be on the front row"- Sen. Cindy Hyde-Smith says in Tupelo, MS after Colin Hutchinson, cattle rancher, praises her. Hyde-Smith is in a runoff on Nov 27th against Mike Espy. pic.twitter.com/0a9jOEjokr — Lamar White, Jr. (@LamarWhiteJr) November 11, 2018

Photos from 2014 then surfaced on Facebook of Hyde-Smith wearing a rebel hat while visiting a museum for Confederate President Jefferson Davis with a caption that said, "Mississippi history at its best!"

I enjoyed my tour of Beauvoir. The Jefferson Davis Home and Presidential Library located in Biloxi. This is a must see.... Posted by Cindy Hyde-Smith on Friday, August 8, 2014

The controversies have prompted a number of donors, including Walmart, AT&T and Pfizer, to ask for campaign contributions to be returned. On Sunday, Major League Baseball asked for its $5,000 donation back, citing Hyde-Smith's controversial comments.

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There has been no comment yet from Johnson or the Giants. He did apologize last month after supporting a Republican super PAC which was making racist radio ads. At the time, Johnson said he didn't realize that's what the group was doing.

Burris says he's a huge fan of the Giants but he believes it's time for fans to withdraw their support for the team.

"I would not be willing to accept an apology that he didn't know because this is the second time it has happened and there is more information about this person," said Burris.

Fans who spoke to KPIX said they are weighing whether they would join the boycott.

"Boycotting seems a bit extreme. But is it extreme compared to a public hanging? I think not," said a fan.