Republican nominee Donald Trump has called her "crazy", "nuts" and "dumb as a rock".
Republicans in Congress disparage her as a diversity hire. Right-wing activists and trolls have smeared her online with racist, sexist and sexualised barbs.
The attacks on Kamala Harris, the first woman and first black and South Asian person to serve as United States vice-president, have intensified in the days since she consolidated support to become the Democrats' likely presidential nominee.
The demeaning racist and sexist attacks threaten to distract from the Republican Party's concerted effort to focus on Harris' policies.
Trump allies, including some members of the Black Americans for Trump coalition, warn that disparaging Harris could hurt him in his outreach to black voters, a crucial demographic in the Nov 5 presidential election.
In interviews with nine Republican lawmakers and 11 black Republican women who back Trump, eight said personal attacks on Harris should be avoided.
While guarded in their comments and emphasising their continued support for Trump, several expressed worry about the tenor of the attacks and whether the onslaught could harm Republicans at the ballot box.
"I think there is a way to critique her without going underneath her clothes," said P. Rae Easley, a black conservative radio show host in Chicago and a member of the Black Americans for Trump coalition, a loosely organised group of black allies backing Trump.
Several members of Congress echoed her sentiments.
"I'm going to oppose Vice-President Harris because of what she's done, not who she is," said Representative Dusty Johnson, who chairs the 75-member Republican Main Street Caucus.
"Some of this ugliness is unbecoming of a great country."
Others said the attacks on Harris' personal life were no different than Democrats attacking Trump on his personal and family life.
"It's a nasty fight. Democrats have a tendency to play victim," said Madgie Nicolas, co-chair of Haitians for Trump and the Faith and Freedom Coalition's national director of African American voices.
The tension suggests Trump campaign efforts to tie Harris to President Joe Biden's record — particularly on immigration, crime and the economy — risk being overshadowed by personal attacks that show no signs of slowing.
"Going after Kamala Harris as a 'DEI hire' is breathtakingly stupid," said Republican pollster Whit Ayres, who has worked on campaigns for US Senator Marco Rubio, Florida Governor Ron DeSantis and others.
"It's going to backfire," Ayres said, adding that Harris had an "incredible array of far left-wing policies" that could be targeted.
DEI stands for diversity, equity and inclusion initiatives aimed at increasing representation of women and people of colour in the workforce to address longstanding inequities and discrimination.
The term DEI hire is used to suggest a person is not qualified for their role and has been chosen on the basis of their race or gender.
Ayres said the disparaging rhetoric would alienate women and "anyone who isn't far-right".
Trump's inflammatory rhetoric has emboldened people with racist beliefs to express them, according to rhetoric experts, critics and past public opinion polling.
The former president has a history of attacking political opponents, including other black women in power, such as Fulton County District Attorney Fani Willis, who is prosecuting his election interference case in Georgia, and US district judge Tanya Chutkan, the judge assigned to the federal case against him for attempting to overturn the results of the 2020 election.
At a rally in North Carolina on Wednesday, Trump did not go after Harris on gender or racial grounds. Instead, he painted a potential Harris presidency in apocalyptic terms.
"She is a radical left lunatic who will destroy our country."
Trump spokesperson Karoline Leavitt said voters would reject Harris not because of her race and gender, but because of her failed policies.
A spokesperson for Harris, whose nascent campaign has generated a groundswell of grassroots fundraising and activism, said she is staying focused on her work.
"These attacks are backfiring and even Republicans know it," said Sarafina Chitika.
* The writers are from Reuters