This week, one presidential candidate has called the other a loser, made fun of him for selling Bibles, and even poked fun at his hair.
That kind of taunting is generally more within the purview of former President Donald J. Trump, whose insults are so voluminous and so often absurd that they have been cataloged by the hundreds. But lately, the barbs have been coming from President Biden, who once would only refer to Mr. Trump as “the former guy.”
Gone are the days of calling Mr. Trump “my predecessor.”
“We’ll never forget lying about Covid and telling the American people to inject bleach in their arms,” Mr. Biden said at a fund-raiser on Thursday evening, referring to Mr. Trump’s suggestion as president that Americans should try using disinfectant internally to combat the coronavirus.
“He injected it in his hair,” Mr. Biden said.
He is coming up with those lines himself: “This isn’t ‘S.N.L.,’” said James Singer, a spokesman and rapid response adviser for the Biden campaign, referring to “Saturday Night Live.” “We’re not writing jokes for him.”
The needling from Mr. Biden is designed to hit his opponent where it hurts, touching on everything from Mr. Trump’s hairstyle to his energy levels in court. Mr. Biden has also used policy arguments to get under Mr. Trump’s skin, mocking the former president’s track record on abortion, the coronavirus pandemic and the economy.
The president’s advisers say Mr. Trump’s legal problems have created an opening. As Mr. Trump faces felony charges that he falsified business records to pay off a porn actress ahead of the 2016 election, Mr. Biden and his aides have refrained from talking directly about the legal proceedings. Mr. Biden has made it a point to say he is too busy.
“I haven’t had a chance to watch the court proceedings because I’ve been campaigning,” Mr. Biden told a group of donors assembled at the actor Michael Douglas’s home in New York on Thursday.
But everyone in the Biden camp — from the president to the officials running his social media accounts — sees the moment as ripe for holding up a split screen between Mr. Trump’s current schedule and the president’s.
As Mr. Biden traveled aboard Air Force One to Florida this week, Andrew Bates, a White House spokesman, told reporters to keep their eyes peeled for updates.
“Nobody fall asleep while we talk, please,” Mr. Bates said, an unsubtle reference to reports that Mr. Trump had dozed off in court.
Jennifer Mercieca, an associate professor at Texas A&M University who studies political rhetoric, said that Mr. Trump has often won supporters with his ability to present himself as a strong, authoritative leader, and that he “always tries to define Biden as sleepy, as old, as senile, the opposite of the strong man.”
She said that Mr. Biden was trying to flip the narrative. At a campaign reception in Dallas last month, Mr. Biden told a group of donors a story about a “defeated-looking” man who had complained to the president about a “crushing debt.”
“And I had to look at him and say, ‘Donald, I’m sorry. I can’t help you,’” Mr. Biden said. “I thought about it, but I just couldn’t do it.”
Still, it remains to be seen if this new approach can change the minds that have already been made up.
The former president may be stuck in a courtroom, but according to recent polls, he is still leading in battleground states. (The Biden campaign equates the polls to ambient noise during a turbulent election season.)
Mr. Biden has also been making comments that draw unwelcome attention to his own tendency to misspeak, exaggerate his past or make public gaffes.
This week he repeated a debunked claim that he used to drive an 18-wheeler truck. On Wednesday, he seemed to read instructions from a teleprompter out loud to his audience, asking them to imagine what the Biden administration and its supporters could do with the next “four more years … pause.”
Mr. Biden also told two campaign audiences that after being shot down during World War II, his uncle might have been eaten by cannibals in Papua New Guinea, angering the island nation’s leaders at a time when the president has been courting them as part of his Indo-Pacific strategy.
But, because it is now April of an election year, the president’s advisers waste no time on explaining the boss’s mistakes, instead throwing them back on his opponent.
“The president had an emotional and, I think, a symbolic moment,” Karine Jean-Pierre, the White House press secretary, said by way of explaining the cannibals comment. She went on to castigate Mr. Trump for calling military veterans “suckers” and “losers.”
Mr. Biden’s advisers say that they are not just making fun of Mr. Trump for their own amusement — they want to highlight policy differences and draw a contrast between the two candidates.
During a campaign speech in Tampa, Fla., on Tuesday, Mr. Biden stayed focused on tying Mr. Trump to laws that have restricted access to abortion and reproductive health care, an issue that is galvanizing for Democrats even as the party remains divided over a range of other matters, from the war in Gaza to border policy.
During his speech, Mr. Biden said Mr. Trump’s name more than a dozen times as he argued for restoring the protections of Roe. Mr. Biden also found a way to make a joke about Mr. Trump’s latest business opportunity.
“He described the Dobbs decision as a ‘miracle,’” Mr. Biden said, referring to the case that sealed Roe’s fate. Then he mocked Mr. Trump’s effort to sell copies of the Bible. “Maybe it’s coming from that Bible he’s trying to sell. Whoa. I almost wanted to buy one just to see what the hell is in it.”
Not every attack landed as cleanly.
“How many times does he have to prove we can’t be trusted?” Mr. Biden said at that rally, presumably meaning to assign the blame to Mr. Trump. The misstep was highlighted throughout the day by conservative media.
On Friday, the Biden campaign capped off the week with an email calling Mr. Trump “the smallest man in the world,” lacing a message with references to songs by the singer Taylor Swift, whose political endorsement the campaign is courting.
Zolan Kanno-Youngs contributed reporting.