Democrat Jon Ossoff and Republican Karen Handel strongly condemned an attack ad that surfaced Sunday accusing the "unhinged left" of endorsing violence against Republicans days before the nationally-watched race to represent Georgia's 6th District is decided.

The ad, funded by a little-known group called the Principled PAC, opens with sounds of gunshots and footage of U.S. Rep. Steve Scalise being wheeled away on a stretcher after he and other members of the Republican congressional baseball team were ambushed by a lone gunman while practicing in a Washington suburb.

"The man is fighting for his life," Ossoff said Sunday after a campaign stop. "I think it's disgraceful to politicize it, and I think Secretary Handel should call for it to come down."

A spokeswoman for Handel, a former Georgia secretary of state, called the video "disturbing and disgusting" in a statement that stopped short of asking for the ad to be removed.

"For any group to use the shootings this week for political or personal benefit is shameful," said Kate Constantini. "This group should be ashamed."

Watch the TV spot here:

The ad urges Republicans to "stop" Ossoff and claims that the "unhinged left is endorsing and applauding shooting Republicans."

"When will it stop?" a narrator asks. "It won’t if Jon Ossoff wins on Tuesday, because the same unhinged leftists cheering last week’s shooting are all backing Jon Ossoff. And if he wins, they win.”

Both candidates have called for more civility after the ballfield shootings in the race to represent Georgia's 6th District, a suburban stretch of north Atlanta that both parties consider crucial to win. It's by far the most expensive U.S. House contest in history, and President Donald Trump and other White House officials have stumped for the Republican.

After Scalise's shooting, the tensions in the race ratcheted up even more. Handel and several neighbors received threatening letters with a white substance the FBI later said was likely not hazardous. Ossoff said he had to hire a security detail amid escalating threats his campaign had received.

The PAC's ad flashes a screenshot of the letter sent to Handel, as well as the image of comedian Kathy Griffin holding a decapitated head that resembles Donald Trump.

Principled PAC bills itself as a group that only supports "principled conservatives who have the backbone to stand up to the Washington elite," but is a bit player in the political world and has faced staunch criticism from conservative leaders. Its five-figure ad buy pales in comparison to the millions pumped into the race by influential groups from both sides of the partisan divide.

Ossoff was asked whether he's worried if these ads might sway voters.

"I can't even think about the politics of it. You've got a national tragedy that's united people," he said. "There are still people who are in critical condition. It's got no place in an attack ad."

More recent AJC 6th District coverage:

National Democrats, Republicans both see 6th District as a must-win

Jon Ossoff: The making of a Georgia Democratic dynamo

Karen Handel: A ‘fighter’ returns to the political arena

First-timers get involved in 6th District get-out-the-vote effort

Exhausted 6th District voters prepare for vote

Trump robocall slams ‘tax-raising’ Ossoff in Georgia 6th race

Georgia 6th District: AJC poll shows Ossoff with lead over Handel