“She left angry, she left mad,” he said. “There was nobody more insulting to Biden than she was.”
One right-wing commentator, Dinesh D’Souza, appeared on Fox News to question whether Ms Harris, the junior senator from California and a child of immigrants from Jamaica and India, could truly claim she was Black. And on Tuesday night, Tucker Carlson, the Fox News host, mispronounced her first name, even growing angry when corrected.
“So what?” he said, when a guest told him it was pronounced “Comma-la.” (Fox News declined to comment on the exchange.)
On Twitter, Eric Trump, one of the president’s sons, favourited a tweet, which was later deleted, that referred to Ms Harris as a “whorendous pick.”
Jenna Ellis, a senior legal adviser to the Trump campaign, posted during Ms Harris’ first speech as Mr Biden’s running mate Wednesday, “Kamala sounds like Marge Simpson.”
Donald Trump added to the barrage with a racist tweet Wednesday morning claiming that Mr Biden would put another Black leader, Senator Cory Booker of New Jersey, in charge of low-income housing in the suburbs.
That tweet did not mention Ms Harris, but it continued Mr Trump’s tactic of playing into white racist fears about integration efforts as he declared, “The ‘suburban housewife’ will be voting for me.”
“They want safety & are thrilled that I ended the long running program where low income housing would invade their neighbourhood,” Mr Trump wrote.
“Biden would reinstall it, in a bigger form, with Corey Booker in charge!” The president did not explain why he referred to Mr Booker, whose first name he misspelled.
But the harsh personal criticisms, and a fixation on Ms Harris’ race, reflected a serious problem for the Trump campaign - its inability to launch a clear attack on the Biden-Harris ticket.
The lack of a frame to respond to the significance of Ms Harris' selection underscored how the president and his campaign, without any senior strategist, are floundering as they try to decipher what their own reelection message should be.
And hours after the campaign and the Republican National Committee called Ms Harris the “most liberal” member of the Senate, the RNC sent out an email blast saying that progressives hated her because she was not progressive enough.
Ms Harris ran her own presidential campaign last year, and was widely seen as the most obvious pick for Mr Biden: at once a conventional and groundbreaking choice.
Despite plenty of time to prepare for her, Mr Trump and his allies appeared to be caught without a coordinated game plan, lurching from one attack to another, when the Democrats finally announced their ticket Tuesday.
Mr Trump’s high-profile female surrogates like former Governor Nikki Haley of South Carolina and Governor Kristi Noem of South Dakota were notably absent from any coordinated response to the announcement, choosing to remain silent.
“Steve Bannon offered a populist North Star for them in the 2016 campaign, and Hillary Clinton gave them a lot of fodder for populist attacks,” said Tim Miller, a former top strategist for former Governor Jeb Bush of Florida.
Mr Bannon was the strategist who worked for Mr Trump in 2016 and helped frame him as the populist candidate on the right.
A 2016 version of Mr Trump might have attacked Ms Harris as a Wall Street-funded coastal elite and a former cop, in an attempt to undermine the Democratic ticket with working-class voters, while also trying to suppress the Black vote.
Sam Nunberg, an adviser to Trump’s campaign early on in 2015, noted that Mr Trump donated twice to Ms Harris when she was a candidate for attorney general in California, where he has business interests.
Mr Trump, he said, could have argued that “he knew how to play the game and he played her,” Mr Nunberg said. “You can’t trust her because she was there at Trump Tower groveling for cash, just like Hillary.”
Instead, the campaign and the RNC were trying to make the argument that the Biden-Harris ticket is both a tool of the far left and despised by it.
“They wanted Bernie and Warren,” Mr Miller said, referring to Bernie Sanders and Elizabeth Warren. “That would have made the attack that the party is enthralled by the left easier. It’s a hard sell to say Joe Biden is a puppet for Kamala Harris, who is a puppet for the Squad.”
Tim Murtaugh, the communications director for the Trump campaign, disputed there was any confusion about what the selection of Ms Harris represented.
“She pushes Biden further to the left than he had already moved by himself,” Mr Murtaugh said, noting her support for sanctuary cities, her opposition to the death penalty even for MS-13 gang members, and her decision as a prosecutor to hand out plea deals while homicides in her city were on the rise.
He said the campaign was not responsible for news releases from the RNC or for commentary on Fox News. “We are focused strictly on talking about how she completes the radical leftist takeover of Joe Biden,” he said.
But some Republicans, including ones often critical of the president, cautioned that presidential tweets and pundit chatter would not have nearly the impact on voters that advertising would. And the Trump campaign’s ability to be more focused and consistent in its messaging online and on television is where it can do the most potential damage by defining an opposing running mate.
“They can’t control Trump,” said Mike Murphy, a media adviser to several Republican presidential candidates. “He’ll be tweeting, name calling — and the difference between this time and last time is that Trump has half a billion dollars in resources at his disposal from the RNC.”
Mr Murphy said that Ms Harris, and her support for certain policies, would be easier for conservatives to attack than their initial, disjointed, response suggests.
“The machinery under the Trump campaign knows how to do the mediocre, standard version of this,” he said. “Kamala Harris is the pick. Here’s the résumé: As attorney general she opposed the death penalty, even for cop killers; as senator, she supported reparations for slavery and said she would take away private health insurance. She is the future.”
On Wednesday, Mr Biden made it clear he expected the campaign to go in the opposite direction, and become more personal.
“Donald Trump has already started his attacks, calling Senator Kamala ‘nasty,’ whining about how she’s ‘mean’ to his appointees,” he said. “Is anyone surprised Donald Trump has a problem with strong women across the board? We know that more is to come.”