The problem with having a current president and two former presidents in your campaign corner is that their gaffes become your gaffes, as Vice President Kamala Harris can attest.

The Harris camp spent Wednesday scrambling to clean up the public-relations mess after President Biden called Trump supporters “garbage,” inflaming the right and upstaging the vice president’s major address Tuesday on the Ellipse, where she called for “unity.”

​It wasn’t the first time Mr. Biden has stepped on Ms. Harris’ messaging. Nor is he the only Democrat with the word “president” in front of his name who has caused headaches for Ms. Harris.

Earlier this month, former President Barack Obama committed a rare communications misstep when he lectured Black men in Pittsburgh over their lack of enthusiasm for Ms. Harris, igniting a backlash among Democrats who accused him of scapegoating one voting bloc.

Former President Bill Clinton appeared to blame the Biden administration for the murder of Georgia nursing student Laken Riley, saying during a Harris campaign stop that if the suspect, an illegal immigrant, and others “had all been properly vetted, that probably wouldn’t have happened.”

The comment set up an easy lay-up for the Trump campaign, which said in an Oct. 14 statement that “Clinton correctly blamed Kamala Harris’ failed border policies for the tragic death of Laken Riley during an event in Georgia Monday.”

Last week, Mr. Clinton again drew national headlines for the wrong reasons on the campaign trail for Ms. Harris in Phoenix when he described Republican Senate candidate Kari Lake as “physically attractive.”

Of course, the ex-presidents may well have done more good than harm on the campaign trail by boosting fundraising and whipping up support with voters nostalgic for their administrations.

A bigger problem for Ms. Harris lies with Mr. Biden, who was essentially pushed aside in July by the Democratic Party in favor of his vice president and has no real role in her campaign.

Earlier this month, Mr. Biden praised Florida Gov. Ron DeSantis for doing a “great job” on his hurricane response, a day after Ms. Harris complained that the Republican governor had failed to return her phone call and accused him of “playing political games.”

Mr. Biden said at an impromptu White House press briefing on Oct. 4 that he and Ms. Harris are in “constant contact” and “singing from the same song sheet,” undercutting her efforts to put distance between them.

Ms. Harris has kept Mr. Biden at arm’s length during the final stretch, spurring speculation that they are at odds — and prompting conservative pundits to ask whether the president is deliberately sabotaging her.

After the “garbage” comment went viral, WMAL-FM radio host Larry O’Connor said Wednesday that “you cannot tell me that Joe Biden didn’t do this on purpose.”

“The man knows politics. He’s been around 50 freaking years,” he said on his show. “You cannot tell me that this was not deliberate. This is the greatest October surprise I’ve ever seen. Joe Biden is absolutely submarining Kamala Harris’ chances, torpedoing it right out of the water. And it’s glorious to watch.”