WASHINGTON (AFP) - Dr Jill Biden promotes Covid-19 vaccines and takes part in political rallies - but only when her college professor schedule allows.
In her quiet way, Dr Biden is reinventing the traditional role of the First Lady of the United States.
Attending a former governor's funeral last week, President Joe Biden had to apologise for his wife's absence.
"The reason Jill is not with me today is she's teaching today, full time as a professor at Northern Virginia Community College," the president said.
The announcement in September that the first lady was resuming face-to-face instruction at her college made headlines in the American press. Never before had a presidential spouse had a professional career outside the White House.
Dr Biden, now 70, married Mr Joe Biden in 1977, when he was a widowed senator with two young boys. The couple later had a daughter together.
A member of the national teachers' union with a doctorate degree in education, Dr Biden continued teaching while her husband served as vice-president under Mr Barack Obama.
Like most educators in the US, she taught remotely during the coronavirus pandemic, before returning to in-person instruction this fall. She now teaches English and writing two days a week.
When she is not in the classroom, the slim, blond-haired Dr Biden can be seen by the president's side at private and public events, but also, more and more often, alone on stage.
The First Lady is travelling around the country urging Americans to get vaccinated against Covid-19 and - ever since vaccines were approved for teenagers and younger kids - to also immunise their children.
She has also campaigned in support of a Democratic candidate in a local election, attended the Tokyo Olympics and was seen in a cafe with Ms Brigitte Macron, the French president's wife, as Washington was caught in a diplomatic crisis with Paris.
"She certainly has been sort of picking up the pace of her public appearances lately," said Associate Professor Tammy Vigil, a media science expert at Boston University's College of Communication. "In the modern era, it's extremely expected of first ladies that they become more and more publicly active."
Mrs Jackie Kennedy sought to preserve America's cultural heritage and famously redecorated the White House. Mrs Nancy Reagan campaigned against drug use. And Mrs Michelle Obama launched a major movement promoting healthy eating and exercise among American children.
By contrast, Mrs Michelle Obama's successor Melania Trump "got into a lot of trouble because she wasn't as active as she should be in terms of public service," Prof Vigil said.
Unlike Mrs Obama, who faced openly racist and sexist attacks, Dr Biden has so far been largely spared aggression - even in today's tense political climate.
That said, she still came under considerable scrutiny.
Earlier this year, CNN published a column on its website urging her to exhibit more "restraint" in her fashion choices, after she was seen wearing a black leather skirt and patterned black tights.
"It's part of her high-profile, first lady job to look dignified. And gracious," psychologist Peggy Drexler opined in the piece.
And in late 2020, the conservative-leaning Wall Street Journal published an opinion piece, calling into question Dr Biden's academic credentials.
"Any chance you might drop the 'Dr' before your name?" the columnist asked. "Dr Jill Biden sounds and feels fraudulent, not to say a touch comic." The piece caused a public uproar for its message and condescending tone.
"The First Ladyship has been behind the times as far as representing what American women do and how they really live," said Prof Vigil, the Boston University professor.
But while Dr Biden pushes the boundaries of her role, she also tries to tread a careful line, mindful that the US first lady is not an elected official and does not possess official powers or duties.
She does not openly meddle in politics, although some commentators see her as the inspiration behind Mr Biden's short-lived initiative to offer two years of free community college to young Americans.
In her day, Mrs Hillary Clinton faced sharp criticism for being too active in promoting healthcare reforms while her husband was president.
If the family life of a US president and the role of First Lady are still subject to "conservative" views in America, Prof Vigil said that other members of Mr Biden's administration are pushing the boundaries in different ways.
Among them is Vice-President Kamala Harris, whose spouse Doug Emhoff is the first-ever "Second Gentleman" of the US. There is also Transportation Secretary Pete Buttitieg, who happily talks about the infant twins he has with his husband.