Kamala Harris’s apparent reluctance to give an extended broadcast interview meant that her sit-down with CNN on Thursday night assumed an exaggerated significance. And placed her under greater scrutiny.

It was not a strong start.

Initially, Ms Harris struggled to lay out what she would do on day one of the job, talking in sweeping generalisations about creating an opportunity economy and trying to lower the cost of living.

Ms Harris has been prone to giving complex, detailed and often confusing answers. Her opponents like to mock her “word salads”. This wasn’t a major issue in this interview, but she will need to craft a more concise explanation of how she intends to make life more affordable for ordinary, working Americans if she wants her message on the economy to land.

Throughout the interview, which she did along with her vice-presidential pick Tim Walz, Ms Harris appeared calm and confident. And, crucially, didn’t score any own goals.

Asked about her shifting positions on some key policies since she last ran for president in 2019, Ms Harris said her values had not changed – before confirming that she no longer supports a ban on fracking for natural gas or decriminalising illegal immigration.

And when addressing Republicans' claim that she is soft on border issues, she pointed to her previous experience as a prosecutor in California. It is experience that Ms Harris often leans on, including in her attacks on Donald Trump, whose criminal conviction she frequently points out.

“I'm the only person who has prosecuted transnational criminal organisations who are trafficking guns, drugs and human beings,” she told CNN's Dana Bash. “I'm the only person in this race who actually served a border state as attorney general to enforce our laws.”

Immigration and the southern border is potentially Ms Harris’s greatest liability in this election. It is an issue many voters care about passionately right across the country – and one on which the Biden administration has had little to boast about given the high numbers of undocumented immigrants at the US southern border.

Joe Biden specifically tasked Ms Harris with addressing the “root causes” of Central American immigration. Republicans have used that brief to claim she was the “border tsar”, and therefore responsible for the record high rates of illegal border crossings in recent years.

When pressed on the issue, Ms Harris told CNN on Thursday that she would resurrect a recent border security bill that was agreed in congress but scuppered by Trump, who told Republicans not to support it. The former president was worried it would damage him politically if the Biden administration was seen to be taking action on immigration.

In reality, that move provided Democrats with a convenient talking point when challenged about why it has taken them so long to illegal border crossings. Ms Harris said she would push that legislation again and make sure it came to her desk so she could sign it.

As she continues to campaign over the coming weeks before the election on 5 November, Ms Harris will have to walk a careful line. Does she talk up her role in the Biden administration? Or present herself as a candidate for change who represents the future not the past?

On Thursday, she was scrupulously loyal to President Biden and did not try to distance herself from his policies. The problem is that if she wants to take credit for lowering the cost of prescription drugs for pensioners, for example, then she also risks taking the blame for high inflation. It is tricky territory.

The Harris campaign often uses the phrase “we’re not going back”. And in this interview, while she was loyal to Mr Biden, she also repeatedly said it was time to “turn the page on the last decade”.

She then had to explain that she meant a decade of bitterness and division, not the last three and a half years of the Biden-Harris administration when she has been in power.

It was a moment that deftly illustrated the challenge Ms Harris faces in presenting herself as a candidate of change.

As Trump has struggled to find a consistent line of attack against Ms Harris, he has resorted to insults. He questioned her racial identity when he said at a recent event that “she happened to turn black and now she wants to be known as black”.

Given a chance to respond directly to that on Thursday, Ms Harris shrugged it off. She said her opponent was using “the same old, tired playbook”. It is almost certainly a deliberate strategy not to engage with Trump’s personal attacks on the first female candidate of colour to be the presidential nominee for one of the major parties.

Ms Harris does not talk about shattering the glass ceiling in the way Hillary Clinton did in 2016. And she says very little about the historic nature of a black woman running for president. She told CNN that she in the race because she believes she is the best person to do the job – regardless of race and gender

Trump, meanwhile, posted his one-word verdict of the interview on his social media platform – "BORING".

The Harris campaign will have taken that as high praise. After all, her most important job was to ensure she did not give Republicans any new ammunition to use against her.