It was Kamala Harris’s first public speech after incumbent Joe Biden withdrew from the United States presidential race — and the vice president spent much of it hailing her boss.

“Joe Biden’s legacy of accomplishment over the past three years is unmatched in modern history,” Harris told a crowd assembled on the White House lawn on July 22, a day after Biden dropped his re-election bid.

“In one term, he has already surpassed the legacy of most presidents who have served two terms in office.”

In the weeks since she made those comments, Harris has been confirmed as the Democratic Party’s presidential nominee. She has also named a running mate in Minnesota Governor Tim Walz, and her campaign has injected enthusiasm into what had been a largely lacklustre election season.

Yet despite Harris’s praise that day at the White House, Biden has largely been absent from her campaign so far — prompting questions about whether his presence on the trail will help, or hinder, her efforts to win the presidency.

“I think Joe Biden will be a sounding board if asked by the Harris campaign,” said Tatishe Nteta, the provost professor of political science at the University of Massachusetts Amherst and director of the UMass Amherst Poll.

He said Biden, who ran a successful presidential campaign in 2020 and spent decades in Congress, will be able to offer advice on “how to both effectively and efficiently leverage” his experience, including by using his connections across key states.

But Nteta told Al Jazeera he doesn’t think it strategically makes “much sense to put Biden up front in the American people again. I don’t see the benefit.”

Biden administration’s record

Biden, who dropped out of the race amid questions about his age and cognitive ability, said last weekend that he plans to campaign for Harris in the battleground state of Pennsylvania. He narrowly edged out his Republican predecessor, Donald Trump, in the state in 2020, effectively winning him the White House.

“I’m going to be campaigning in other states, as well. I’m going to be doing whatever Kamala thinks I can do to help most,” the US president told CBS News on Sunday.

Biden is also set to speak on the first night of the Democratic National Convention, which runs from August 19 to 22 in Chicago.

He will no doubt use that address to heap praise on Harris while also touting the successes of his administration, including the passage of major pieces of legislation such as the Bipartisan Infrastructure Law and the Inflation Reduction Act.

But Biden has also been widely criticised on a number of issues during his term, from the surge in the number of migrants and asylum seekers crossing the US-Mexico border to his staunch support for Israel as it wages war in the Gaza Strip.

He remains a target of attacks by Republican lawmakers and Trump, the GOP’s 2024 presidential candidate — and some of their anti-Biden talking points have shifted to Harris in the wake of her presidential bid.

Republicans have particularly slammed her record on immigration, falsely dubbing her the administration’s “border czar”. In reality, she had no authority over the border but was tasked with addressing the “root causes” of migration to the US from parts of Central America and Mexico.

Harris also has faced sustained protests from key segments of the Democratic Party base over the administration’s Israel policy. Advocates have publicly urged her to back an arms embargo against the top US ally in response to its deadly military attacks across Gaza.

“I think the genocide in Gaza that’s been going on has been a real tarnish on Biden’s legacy,” said Hasan Pyarali, the Muslim Caucus chairperson for College Democrats of America, the university arm of the Democratic Party.

As a result, having Biden on the campaign trail risks hurting Harris, Pyarali told Al Jazeera. He said he believes Harris should make a clear break from Biden’s stance on Israel.

“I think, in this case, that she has a really rare chance in politics to rebrand and take on a new identity as more progressive, as more youth-minded.”

Policy, not just ‘vibes’

But both Pyarali and Nteta said that — while the Harris campaign has been able to build strong momentum in its first weeks, thanks in part to a strong social media presence — it will need to go beyond rhetoric and lay out clear policies to appeal to voters.

“She has been putting out memes, but memes only get you so far,” said Pyarali.

He stressed that this is particularly pivotal with the issue of the Gaza war. Pyarali said that Harris must break from Biden on Gaza “and call not just for a ceasefire but an arms embargo on Israel until this war is over”.

On Tuesday, the Biden administration announced it had approved the potential sale of more than $20bn in weapons to Israel, drawing fresh rebuke.

“Short of a policy change, you’re going to run up a lot of the same issues that Joe Biden did,” Pyarali said. “She has a chance here to really unite the party behind a new progressive vision for peace, and I hope she takes it.”

Nteta said he believes Harris should still highlight the Biden administration’s successes and her role in them, but she likely intends to strike out her own in order to appeal to Americans who had been frustrated with their previous options in the presidential race.

Biden had originally been set to take on Trump — whom he defeated in 2020 — in what one political science expert had dubbed “Election 2.0”, effectively a “rematch” between the two men.

But voters had signalled limited enthusiasm for the options. A Pew Research Center poll from April indicated nearly half of all registered voters would have replaced both Biden and Trump on the ballot if they could.

In early August, a UMass Amherst poll found 66 percent of respondents who backed Harris’s candidacy said they did so because she “represents a new generation”. If elected, Harris would be the first woman and the first Black and South Asian woman to serve as US president.

“People are looking for something distinct, something new,” said Nteta.

Harris, he added, will soon need to “start articulating what her policy positions are rather than just overarching positivity, enthusiasm and energy”.

“I think defining who she is, is necessary,” he told Al Jazeera, “because at this point in time, Americans are really responding to vibes and not necessarily to policy.”