Who wouldn’t want Valerie Biden Owens in their corner? The first sister of the United States gives no inch in defending her big brother. Asked about Joe Biden’s notorious gaffes, for example, she simply rejects the premise.

“He doesn’t have gaffes,” she insists. “He speaks the truth. Like, hello, surprise, I just said what was true!”

At the end of a carefully crafted speech last month in Warsaw, Poland, the president ad libbed that Russian leader, Vladimir Putin, “cannot remain in power”. To the world’s media it was a howler implying regime change that upended weeks of diplomacy and sent aides scrambling.

To Biden Owens, however, it was truth-telling after meeting refugee mothers and children.

“This is a man, you see what you get,” she says, with recognisable flintiness. “His wife died. Two of his children died, one by a long death and one by a sudden death. And one almost from addiction. He was speaking from his heart. What kind of man [Putin] does this? That’s the real Joe Biden. That was not a gaffe.”

Biden Owens, 76, is talking about her newly published memoir. Growing Up Biden is a lucid account of a middle-class childhood remarkable only for its ordinariness, becoming the first woman in US history to run a presidential campaign, and helping “Joey” emerge from personal and political disasters to reach his own mountaintop.

It is also a moving portrait of sibling love. Joe is the oldest of four Biden children. Valerie was born three years later, followed by Jimmy and Frank.

“At an age when a lot of other older brothers pretended they didn’t even know their sister, Joey took me everywhere with him,” she writes. “When his friends would ask, ‘Why did you bring a girl?’ he answered, ‘She’s not a girl. She’s my sister. If you want me around, she’s going to be around, too.’”

Family life began in Scranton, Pennsylvania but work dried up for Joe Biden Sr, who found opportunities in Delaware, cleaning boilers and selling cars. The Bidens moved to a two-bedroom apartment there when Joe was 10.

Valerie’s book does not dwell long on her brother’s childhood stutter but, via Zoom from her home in Kennett Square, Pennsylvania, she elaborates.

“I don’t remember as a little girl that he stuttered; he was just my big brother. But as I got older then I saw that he was a stutterer. I could hear it and I was aware that he was made fun of and that he was made to feel less and put in a corner.

“When you’ve been bullied, you have two ways to go: you can become a bully yourself or you can realise that we’re all in this together and there’s more to life than kicking somebody who’s down. So my brother, layer by thin layer, developed a backbone of steel and determined that he was not going to be defined by a bully.”

How did their parents react to it?

“Contrary to what he had incoming – because he stuttered, he was stupid – my mother said, ‘Oh no, Joey, it’s because you are so smart, you can’t get the words out fast enough’. So my mother gave him confidence. When a person stutters the natural inclination is to jump in and say the word for them but we didn’t do that.”

Joe spent hours alone in front of a mirror, reciting Irish poetry. “He spit the stutter out. He worked at it. In the end, adversity builds character. My brother turned out to be the man that he is with such great empathy because he was a stutterer, so that turned out to be one of his best gifts in hindsight.”

Joe worked as a lawyer, joined the county council and became known in Democratic politics in Delaware. Fifty years ago last month, he announced that he would challenge a popular incumbent for a US Senate seat. Valerie, a 26-year-old high school teacher, ran his long-shot election bid.

It must have been hard going, in a year that would produce campaign accounts with titles such as The Boys on the Bus?

She reflects: “Politics was a boys’ club. Women in in the 1970s and through that period only opened and closed headquarters and got coffee and ordered the paper.

“There were few women candidates. There were no women consultants or women campaign managers or even women journalists with rare exceptions. It was a brand new world for a woman but I had it a lot easier than a lot of women because my brother pulled up a chair for me at the table of all men and said, ‘This is my sister. She speaks for me. She’s the boss. What she says goes, nothing passes through or gets out of here unless she approves.’

“It wasn’t because I was such a brilliant campaign strategist because I had never met a campaign manager before – nor had Joe and I really ever met a United States senator before. It was because I had a PhD in my brother. I knew Delaware, I knew my brother, I knew what the issues were and I knew how we wanted to present what we stood for and I knew how to listen to the people in Delaware who told us what they needed.

“I had it easier until Joe left the room and then there were always doubters who looked at me as either the token relative or the token sister. But I was raised with a wonderful, decent man who was my father and three brothers, so I was not intimidated by men. I enjoyed them and I realised we’ve got to work together.”

Biden won that first election by 3,163 votes, or less than 1.5%. Six weeks later, his wife Neilia and baby daughter, Naomi, were killed when their car collided with a tractor trailer. His sons, Beau and Hunter, were seriously injured but survived.

His sister’s most vivid memory of that day is the clack, clack, clack sound of hers and Joe’s heels as they hurried through the marble hallway of the US Capitol minutes after getting the call from their brother Jimmy. She writes: “Joe turned to me, eyes stricken, voice choked. ‘She’s dead, isn’t she?’ I remember his eyes. I wish I didn’t. Staring into them at that moment was like staring straight into hell.”

She adds now: “My mom always said the eyes are the windows of the soul and I was looking into two dark, dark spaces, because he knew. It was horrible.

“On 7 November, my brother was the too-young-to-serve newly elected senator from Delaware, 29 years old, the hope of the future of the Democratic party, had a beautiful wife, three magnificent children, and six weeks later the whole world turned on its axis. He was a young man whose heart had been ripped out. A young widower.

“Life has a way of interrupting. You think you’re in control and then, bam. My dad said that’s when you’ve got to get up and keep moving. Joe had to get up because he had Beau and Hunter, his two sons, who were just ready to turn three and four years old, so he had a purpose.”

Valerie moved in and helped raise the boys. She also guided Joe – who married Jill Jacobs in 1977 – to six more Senate terms, although they fared less well running for the White House. In the 1987 presidential campaign, he was accused of plagiarism after quoting the British politician Neil Kinnock but forgetting to credit him.

Biden Owens recalls: “The whole incident of Neil Kinnock hurt me a lot personally because it went after my brother’s character and it was a slip of the tongue of omission. Joe should have said it and he didn’t and so he took the hit for it.”

Joe ran a short campaign for the 2008 nomination but after eight years as Barack Obama’s vice-president he opted not to run in 2016. His sister suggests this had more to do with another tragedy, the death of his 46-year-old son, Beau, from brain cancer than discouragement from Obama.

“We wanted to run for president but my brother hadn’t had time to heal and the way that we heal is as a family. What choice is there: to be with your son who you know has been given a death sentence or be out talking to the primary voters in New Hampshire? Just no choice. You have to go through a period of grief and mourning. Every person does it differently but the presidency was not on the cards for us.”

‘Swings and misses’

Joe wears Beau’s rosary on his left wrist every day. His sister insists that loss upon loss has not shaken their faith in God’s existence.

“For me, being a Catholic is a package and, if you believe in the afterlife, it still is pretty hard. Particularly when Beau died, I remember yelling, ‘Why God, what possible good could come from this?’ It was a heart wrenching cry.

“A friend of mine said to me maybe it’s because where he is now, he’ll be able to do even more good than were he with you on Earth. It gave me pause because it’s part of the story of the resurrection and life after death. I didn’t lose my faith because I, Valerie Biden Owens, need something bigger to hold on to than herself.”

It looked like the end of the road for Joe’s political ambitions. But then, Hillary Clinton lost to Donald Trump and the sight of white nationalists marching through Charlottesville, Virginia, galvanised Biden for one more bid. Yet again, there was a rocky start.

At a Democratic debate in Miami in June 2019, the California senator Kamala Harris challenged Biden’s opposition to mandatory desegregation busing in the 1970s, telling the story of a girl who was part of schools’ racial integration and ending with dramatic effect: “That little girl was me.”

Biden Owens was not impressed. “Being a campaign manager, I know sometimes your candidate swings and misses. That was a swing and a miss and certainly it was not an accurate representation but it was a campaign. Immediately in the fallout, it was clear that was not a smack to Joe.”

Biden went on to win the primary with significant support from Black voters. Bearing no grudge, he picked Harris as his running mate. His sister adds: “Look, my brother’s a smart man. He had been vice-president and he knew what it took and what he needed as his partner, and he chose her. So it all was OK.”

This time the campaign was managed by Greg Schultz and then Jen O’Malley Dillon, with Valerie as adviser. She admits she had been hesitant about her brother running because Trump was sure to launch vulgar and dishonest attacks on the family.

Sure enough, Republicans obsessed over Hunter’s business dealings in Ukraine, which included high-paid consultancies and gifts, alleging without evidence that Joe abused the vice-presidency to enrich his son. There is still a frenzy over emails and photos found on a laptop abandoned by Hunter at a repair shop in Delaware in April 2019. Hunter did confirm that he was under federal investigation over a tax matter. He also wrote a memoir of his struggles with addiction.

His aunt does not watch the rightwing media onslaught. “It’s been the same story for four years,” she says. “There’s nothing new. It’s the same one, same one, same one, same one. And by the way, the president has never been accused of any indication that he’s done anything wrong.

“It’s the same accusations they’re dishing out. If that’s how they hope to win as opposed to anything that’s positive, what the hell difference does that make to the ordinary American who’s worried about food or medicine and education for their child? Who cares? Talk about something that matters, Republican party. Step up to the plate. Help middle-class America.”

Perhaps voters agree. The attacks on Hunter never quite stuck like the “Lock her up!” attacks on Clinton. Biden won the White House, promising to heal “the soul of America” after four years of American carnage.

There have been accomplishments for sure – a coronavirus relief package, a record 7.9m jobs created, a $1tn infrastructure law and a reassertion of America on the global stage – but disappointments persist on the climate crisis, police reform and voting rights in a Congress where Democrats’ majority is wafer-thin.

Biden Owens reflects: “What I think was mom’s most profound statement was ‘beware the righteous’ and we’ve got them on the right and we have them on the left equally now. I don’t know how these men and women in Congress are married, how they stay married. Compromise is not a dirty word. It doesn’t mean giving up your principles; it means rubbing off those rough edges.

“It’s been a very difficult time and we’re all just trying to keep our head above water. But when you look at what Joe’s done – more jobs, more judges, more diversity, first woman vice-president, first African American woman on the [supreme court] bench – Joe remembers his roots. He’s a middle-class, ordinary American who had opportunities to do an extraordinary thing, becoming president. He’s got his eye on the ball, which is middle class America.”

‘All Republicans aren’t bad guys’

The president has been criticised, however, for relying on an old operating system in which compromise was possible and failing to recognise that today’s Republican party has embraced Trump’s authoritarianism and lies.

“What puzzles me is this: what happened to Lindsey Graham?” Biden Owens writes, referring to the Republican senator for South Carolina. “After John McCain died, perhaps a part of Senator Graham’s soul died as well. The man is unrecognisable to me.”

She elaborates via Zoom: “I don’t know Lindsey Graham well but, to me, the good guy, the decent person, a large portion of that left him. The Republican party has become a party of a personality cult.

“All Republicans aren’t bad guys and there are good men and women who are Republicans and God bless them because that’s what we got to do to keep our democracy working. But the kissing the ring of the former president, I don’t understand it. It’s there and it’s something to be dealt with. But I have hope that the good men and women will stop this slide.”

Valerie, who is married to Jack Owens, a lawyer and businessman, and has three children, says her brother will run again in 2024 and the question of his age – he turns 80 this year – is for the voters to decide. Early in her book, she reflects matter-of-factly that she lived the first 40 years of her public adult life in his shadow.

Does she have any regrets – and wonder, perhaps, if she could have been President Biden? She quotes the novelist Edith Wharton: “There are two ways of spreading light: to be the candle or the mirror that reflects it.”

She explains: “That’s me and Joe. Sometimes he was the candle, sometimes I was the mirror, but it also flipped. My light was never snuffed out. My life was doing what I wanted to do and what I could do best. I could talk about Joe Biden much better than Joe Biden could talk about Joe Biden.

“People could take the measure of the man or not and he got to do what he did best, which was go out, listen to the voters, tell what he was about and be the best Joe Biden that he could be. So no, it was a wonderful partnership and I wouldn’t have changed it.”

• Growing Up Biden is published in the US by Celadon