(The Hill) — Vice President Kamala Harris has enjoyed a remarkable surge of political energy since President Joe Biden stepped aside from his reelection bid a little more than a month ago.

Harris quickly tightened her grip on the presidential nomination, surfed a wave of Democratic enthusiasm and benefitted from a massive fundraising infusion.

More recently, Harris’ selection of Minnesota Gov. Tim Walz (D) has been well-received while last week’s Democratic National Convention in Chicago acted as a strong showcase for her candidacy.

All of this has propelled Harris into a polling lead. 

In the polling averages maintained by The Hill and Decision Desk HQ (DDHQ), Harris leads former President Donald Trump by roughly four points nationwide. She is also up, by narrower margins, in three key battleground states: Michigan, Pennsylvania and Wisconsin.

But no one expects the period between now and the election to be plain sailing. Harris has said she considers herself an underdog.

Here are five major looming challenges.

A debate with Trump

The first — and perhaps only — debate between Harris and Trump is the next big landmark on the road to Election Day.

Right now, the clash is set for Sep. 10 on ABC News.

However, the fate of the debate has been cast into doubt amid a dispute over rules.

The Trump campaign wants to retain the rules that governed the now-infamous June 27 clash with President Biden. In that instance, when one candidate was speaking the microphone of the other candidate was muted.

The Harris campaign wants to change this agreement, leaving both candidates’ microphones open throughout.

There has, predictably, been sniping between the two campaigns, with accusations flying about who is running scared of whom.

Still, the consensus is that the debate will go ahead. 

Harris, a former prosecutor, will fancy her chances of landing some blows on Trump. 

But debates are inherently unpredictable and Harris didn’t shine especially brightly in the 2020 Democratic primary debates — save for one moment where, ironically, she scored against Biden over his past opposition to school busing.

Her first big TV interview

Harris’ failure so far to grant a major interview has given conservatives some rhetorical ammunition.

Campaign events and convention speeches don’t expose a candidate to searching questions, they note. Harris has so far limited her media availability to brief “gaggles,” which rarely feature tough questions and provide almost no opportunity to follow up.

In one such gaggle, however, Harris said she had told her team to “get an interview scheduled before the end of the month.” 

The ambiguous phrasing left unclear whether the interview is to take place in the next few days or whether it is merely to be agreed upon by then.

In any event, her first big interview will be a high-stakes moment for Harris.

A June 2021 interview between Harris and Lester Holt of NBC News went badly for the vice president when she reacted defensively to a predictable question about why she had not visited the border.

How to explain her shifts in position

Any adversarial setting, whether a debate or a serious TV interview, will see Harris come under pressure over issues on which she has changed her position.

There are a number of topics where that is the case.

Harris supported a ban on fracking when she ran for the Democratic nomination in 2020. She no longer favors such a move, a shift first reported by The Hill.

During the 2020 primary campaign, she also indicated she did not believe people who crossed the border without authorization had committed a crime. She now hews to a tougher position on border security.

Harris, as a senator, was among those who backed a so-called “Medicare-for-All” proposal on healthcare. She is no longer pushing that idea.

Harris will have to explain her reasoning behind these shifts, even while skeptics allege they were driven by political expediency.

Dealing with Trump’s negative ads

The political ad war is sure to ramp up as Election Day nears — and that means Harris will have to fight off millions of dollars in negative advertising.

Ads from the Trump campaign have so far hit Harris on her economic record, her “liberal ideas,” her role in advising Biden during the chaotic withdrawal from Afghanistan, and even her aping Trump’s plan to make tips exempt from income tax.

There will, undoubtedly, be plenty more attack ads to come.

Team Trump campaign had $327 million in cash on hand as this month began, much of which will be spent on the TV air wars.

Harris has vast resources to battle back. Her campaign and its affiliated groups had $377 million cash on hand entering August, and they say they have enjoyed another boost around the Democratic National Convention.

But the danger is that Trump’s lines of attack could gain traction against her.

Winning the center ground

There’s no question that Harris has enthused the Democratic grassroots. But the election will be decided by a small sliver of voters in the battleground states.

One of the big, overarching questions of Harris’s campaign is whether she can capture the center ground — or whether she is vulnerable to the GOP attack that she is so progressive as to be out of step with the American mainstream.

She made a big play for the center in her convention speech, which sounded some overtly patriotic themes and staked out carefully balanced positions on contentious topics from immigration to Gaza.

But much will hinge on whether Harris can sustain that approach and make it stick.