Mark Z. Barabak and Melanie Mason, Tribune News Service

Kamala Harris was conflicted. The California senator needed a big splash in the first Democratic presidential debate, and her main rival, front-runner Joe Biden, seemed to have teed up a perfect opportunity. Days earlier, at a New York City fundraiser, he reminisced of a bygone era in the Senate and his ability to work civilly alongside two segregationist lawmakers.

Harris, only the second Black woman ever to serve in the chamber, was deeply offended. But she also had warm feelings toward Biden, a friend and past political ally.

Her decision to call him to account before a national prime-time audience produced one of the most electric moments of the 2020 campaign and, more than a year later, continues to echo as the presumptive Democratic nominee chooses his vice presidential running mate. Harris is seen as a top contender.

The heated exchange on a tropical June night in Miami, however, has complicated Harris’ hopes of landing on the ticket, even as Biden appears — at least publicly — to have forgiven his former rival.

More broadly, the clash and deliberations leading up to it suggest the approach Harris would take as Biden’s running mate — a style not far removed from her days as a prosecutor, when she relied on meticulous preparation, a dramatic presence and the willingness to set aside personal feelings to do whatever was needed to prevail.

“It’s kind of like being in the courtroom,” said an associate from Harris’ days as California attorney general, who described her capacity to compartmentalise. “You might have the utmost respect and good relations with the defence attorney or the public defender. But you’re there to win.”

Harris declined to be interviewed. But numerous people involved in her presidential candidacy spoke for this article; most wished not to be identified in order to freely discuss the campaign’s internal workings.  Some praised her debate performance, saying it showed Harris’ tenacity and strength in the spotlight and separated her from the sprawling pack of Democratic contestants.

“She proved she is somebody who can throw and land a punch,” said Brian Brokaw, a longtime Harris strategist who ran an independent political action committee supporting her presidential bid. “One of the attributes you want is somebody who doesn’t shy away from a fight and taking on people in power. That’s something she has demonstrated time and time again.”

Others were more critical, saying Harris’ genuine anguish over Biden’s remarks on working with Southern senators was overshadowed when she raised another issue, school busing, and then muddled their differences and undercut her attack.

Some Biden backers, meantime, continue to nurse hard feelings, believing Harris — who was good friends with Biden’s late son, Beau — unfairly blindsided him. They have lobbied against selection of California’s junior senator, one of half a dozen or so women floated as potential running mates.

Biden has said he would announce his pick sometime around Aug. 1. Whether she is chosen or not, Harris’ initial debate performance remains a defining moment of her time on the presidential stage. She launched her candidacy in January 2019 with a massive Martin Luther King Jr. Day rally in Oakland and immediately emerged as a top contestant for the White House. But by the time the first debate rolled around six months later, her campaign was adrift and Harris had fallen back in the Democratic field as others, most notably former South Bend, Indiana, Mayor Pete Buttigieg, captured the imagination of voters.

The debate was seen as a relaunch of sorts. Harris’ strategy for claiming the Democratic nomination had always been to get past the opening contests in Iowa and New Hampshire, win Nevada, then prevail in South Carolina, quickly building momentum from there.

The problem was Biden’s deep ties to the Palmetto State and loyal following among South Carolina’s large Black electorate. The debate offered Harris a chance to take on Biden directly and, by highlighting his comments about working with segregationist senators, seek to undermine his Black support.

But Harris was concerned. She liked and respected Biden a good deal and said during debate preparations she did not wish to portray him as a racist.

“The conundrum was how to go after someone ... she had a long-standing relationship with,” said one political adviser. “How do you go on the attack without doing it in such a way that you burn any and all bridges?”

Harris’ solution was to begin with a direct statement when she faced Biden onstage. “I do not believe you are a racist,” she said, then continued. “I also believe, and it’s personal ... it was hurtful to hear you talk about the reputations of two United States senators who built their reputations and career on the segregation of race in this country.”

Angling her body toward Biden, she said he worked with those senators to oppose school busing as a means of desegregation. “There was a little girl in California who was part of the second class to integrate her public schools, and she was bused to school every day,” she said. “And that little girl was me.”

It was not a new revelation. Harris had often spoken of that chapter of her life, growing up in Berkeley, but it landed with force. Biden looked flustered, then angry. “I was prepared for them to come after me,” he said later on CNN. “But I wasn’t prepared for the person coming at me the way she came at me.

“She knew Beau,” Biden added. “She knows me.”

The Biden campaign accused Harris of criticising him for holding essentially the same position. While that was not entirely true — the assertion overlooked Biden’s actions opposing busing in the 1970s and 1980s — it blunted Harris’ attack, dissipated her momentum and took a good bit of the glow off her debate performance.

The two moved on. Biden apologized before Black voters in South Carolina for his comment about segregationist lawmakers. Harris slowly fell out of contention.

On the occasions their paths crossed the two were friendly, according to people who joined them on the campaign trail. When Harris quit the race in December, Biden called her up and afterward offered kind words. “She is really a solid, solid person and loaded with talent,” he told reporters.

Asked about their heated debate exchange, Biden said, “I’m not good at keeping hard feelings.”

Appearing last month on the “The Late Show with Stephen Colbert,” Harris was pressed about her criticism of Biden and how the two seem to have mended their relationship.

“How do you go from being such a passionate opponent on such bedrock principles for you and now you guys seem to be pals?” Colbert asked.

“It was a debate,” Harris said, laughing, then repeated the point several more times.

When Colbert persisted, Harris turned serious.

“I’ve known Joe a long time and I care about him deeply,” she said. “And as you know we all have family members or friends with whom we have disagreements. That doesn’t overcome or overshadow the commonality between us and the connections between us.”

“I am,” Harris said, “1,000% supportive of Joe Biden.”