US vice president Kamala Harris is trying to outmanoeuvre former president Donald Trump and address old vulnerabilities on her policy positions as she begins to fill in how she would govern if elected in November.

Vice presidents rarely have policy portfolios of their own, and almost always set aside any views that differ from those of the Oval Office occupant.

Now, after four years of following President Joe Biden’s lead, Ms Harris is taking a cautious approach to unveiling a policy vision in her own right.

But her surprise ascendance to the top of the ticket after Mr Biden dropped his re-election bid also means her policy platform is being pulled together just as quickly.

When Ms Harris inherited Mr Biden’s political operation in late July, the campaign’s website was quietly scrubbed of the six-point “issues” page that framed the race against Mr Trump, including expanding voting protections and restoring nationwide access to abortion.

Instead, Ms Harris has peppered her speeches — so far heavy on biography for herself and her running mate — with broad goals like “building up the middle class”.

She has called for federal laws to provide abortion access and ban assault-style weapons, but has been thin on the details of what specifically they would entail or how she would persuade Congress to make progress on some of the most hot-button political issues.

Asked by reporters on Saturday when she would unveil her policy platform, Ms Harris promised more details this week and added: “It’ll be focused on the economy and what we need to do to bring down costs and also strengthen the economy overall.”

The first major window into her thinking came this past weekend, with a proposal pulled not from the policy backwaters of the Biden administration or the cutting-room floor of the legislative process but from her rival: Mr Trump.

Ms Harris announced that she, like Trump, wants to end federal taxation of tipped earnings for workers — with the added caveat that she would limit the plan to those in the lower- and middle incomes.

The idea has drawn bipartisan support in recent months and is particularly salient in service industry-heavy Nevada.

It’s also one of the most prominent ideas embraced by Mr Trump in his 2024 bid to get back into the White House — a bonus in the view of the Harris camp, which has tried to needle the Republican into making unforced errors.

The Republican was none too amused by Harris endorsing the idea, complaining on his social media platform that “This was a TRUMP idea – She has no ideas, she can only steal from me”.

Mr Trump continued on the matter in an interview with Elon Musk on Monday night, criticising Harris for adopting his idea after what he claimed was harassment by the Biden administration of tipped workers.

On Monday, the White House said that Mr Biden backed the plan too, though White House press secretary Karine Jean-Pierre would not address why Mr Biden and Ms Harris did not push for it during their first three-and-a-half years in office.

“Obviously, it’s a new idea,” she said, but added later in response to criticism from Mr Trump: “Why didn’t they pass it during the last administration?”

In her first weeks as a candidate, Ms Harris’ most pronounced policy moves have been to back away from liberal stances she took in her failed 2020 bid for the White House, including proposals to ban fracking, establish a single-payer healthcare system and decriminalise illegal border crossings.

Ms Harris dropped out of that heated race before a single vote had been cast but recognises that voters now could punish her for those stances if not quickly addressed.

Another complication for Ms Harris comes from her relationship with Mr Biden, who quickly endorsed her and handed her the keys to his political operation after he dropped out.

“The last three and a half years, they’ve been in sync,” said Jean-Pierre.

“They have been certainly on the same page. And I presume that that will continue from here.”