Ever since Vice President Kamala Harris took the baton last Sunday from her boss, President Biden, and instantly became the Democratic Party’s new de facto presidential nominee, she has enjoyed one of the most significant “honeymoons” in recent U.S. campaign history.

As a result, the latest polls show Harris closing the gap with Donald Trump in key swing states; pulling even nationally; and surpassing him in terms of favorability and enthusiasm.

Yet all honeymoons come to an end. If Harris hopes to win in November, she will have to differentiate herself from Biden — and convince a decisive number of voters to reject four more years of Trump.

In an attempt to do just that, Harris and her allies have been testing out five main lines of attack: that Trump is "weird"; that he is old; that he is scared to debate; that he is a felon; and that his "Project 2025" agenda is extreme.

Harris has been so committed to these themes that even when Trump questioned her race Wednesday — falsely claiming that she suddenly "made a turn" and "became a Black person" after "only promoting [her] Indian heritage" — she refused to get sucked into a culture war.

"The American people deserve better,” is all Harris said in response.

Meanwhile, Harris's relentlessly on-message campaign used "Trump's tirade" as an opportunity to ding his "harmful Project 2025 agenda" and challenge him to "actually show up for the debate on September 10."

More on the strategic contrasts Harris is trying to draw:

Trump is ‘weird’

When Biden was running, he constantly called Trump a “threat to democracy.”

Harris hasn't left that line of attack entirely behind. "Do we want to live in a country of freedom, compassion and rule of law, or a country of chaos, fear and hate?" the vice president asked at a recent rally.

But for the most part, Harris and her allies have pivoted to a different anti-Trump message — one that comes across as a lot less alarmist and a lot more … dismissive.

"Some of what [Trump] and his running mate [JD Vance] are saying, it is just plain weird," Harris said Saturday at her first fundraiser. "I mean that's the box you put that in, right?"

The new term caught on after Democratic Gov. Tim Walz of Minnesota — who has been using it for months — called Trump, Vance and their policies "weird" a few times last week.

"Listen to the guy," Walz told CNN, referring to Trump. "He's talking about Hannibal Lecter, and shocking sharks, and just whatever crazy thing pops into his mind. And I thought we just give him way too much credit."

Now other Harris surrogates are using it too, especially in reference to some of Vance's recent remarks — and Walz has reportedly become one of Harris's VP finalists.

So far, the "weird" attack has frustrated Republicans, "leading them to further amplify it through off-balance responses," David Karpf, a strategic communication professor at George Washington University, told the Associated Press.

It "makes voters feel like Trump is out of touch," added Brian Ott, a professor of communications at Missouri State University, in an interview with Newsweek. And "it's hard to claim that it is in any way out of bounds politically, which makes any response to it seem like an overreaction and, well, weird."

Trump is old

The first time the Harris campaign officially referred to Trump as “weird” was in a press release put out just days after the vice president announced her candidacy. But there was another, more familiar adjective alongside it.

“Trump is old and quite weird,” the statement said. “After watching Fox News this morning, we have only one question, is Donald Trump OK?”

As everyone knows, Biden is the oldest president in U.S. history; at 81, he was also on track to become the oldest presidential nominee in U.S. history until he ended his campaign last Sunday.

Now Trump, 78, has taken his place.

And so Harris, 59, has turned the tables and started describing the former president as someone who is “focused on the past” — while she, in contrast, is “focused on the future.”

For its part, the Harris campaign has been less euphemistic about the nearly two-decade age gap between the two candidates.

"Tonight, Donald Trump couldn't pronounce words … went on and on and on, and generally sounded like someone you wouldn't want to sit near at a restaurant, let alone be president of the United States," Harris spokesperson James Singer said after a recent Trump speech. "America can do better than [Trump's] bitter, bizarre and backward-looking delusions."

Trump is scared to debate

On Sept. 10, Trump and Biden were scheduled to debate for the second time this year. But after the president withdrew from the race — and Harris emerged as the new, de facto Democratic nominee — Trump started to backtrack.

“I haven’t agreed to anything,” Trump said on a press call last week. “I agreed to a debate with Joe Biden.” Around the same time, the former president suggested that ABC News should no longer host, calling the outlet “fake news.”

Harris immediately snapped back. "What happened to 'any time, any place'?" she said in a post on X.

Since then, Trump has said "The answer is yes, I'll probably end up debating" — while adding that he "can also make a case for not doing it."

In response, Harris has seized on Trump's waffling as evidence that "the momentum in this race is shifting" and that "Trump is feeling it," as she put it Tuesday during a rally in Atlanta — effectively weaponizing the whole situation to question Trump's confidence.

“Well, Donald," Harris said in Atlanta, addressing Trump directly. “I do hope you'll reconsider. Meet me on the debate stage ... because as the saying goes, if you've got something to say, say it to my face.”

Trump is a felon

Harris debuted as a 2024 presidential candidate last Monday with an appearance at campaign headquarters in Wilmington, Del. She spoke for about 20 minutes — but one passage in particular got the lion's share of attention.

“As many of you know, before I was elected as vice president, before I was elected as United States senator, I was the elected attorney general, as I’ve mentioned, of California,” Harris said. “And before that, I was a courtroom prosecutor.”

"In those roles, I took on perpetrators of all kinds," the candidate continued, as laughing, applauding staffers began to realize what was coming next. "Predators who abused women. Fraudsters who ripped off consumers. Cheaters who broke the rules for their own gain. So hear me when I say: I know Donald Trump's type."

Since then, Harris has used the same lines in every stump speech she’s delivered.

Biden, of course, would mention Trump's civil and criminal cases on the campaign trail. But Harris's résumé lends itself to a novel "prosecutor vs. felon" dynamic — one she could further emphasize by picking any of the former state attorneys general on her vice presidential shortlist when she reveals her running mate next week.

Trump’s Project 2025 agenda is extreme

For months, the Democratic Party has sought to tie Trump to Project 2025, a voluminous blueprint for a second Trump term that was created by the Heritage Foundation (a right-wing think tank) with input from at least 140 people who worked for Trump during his first term.

The reason is obvious. Democrats believe Project 2025 policies — deporting millions of immigrants, eliminating the Department of Education, installing loyalists throughout the federal bureaucracy, reversing federal approval of the abortion pill mifepristone — will be unpopular with the public.

Trump, meanwhile, seems to have come to the same conclusion. After Heritage Foundation president Kevin Roberts recently said America was "in the process of the second American Revolution, which will remain bloodless if the left allows it to be," Trump took to his Truth Social network to distance himself.

“I know nothing about Project 2025,” the former president claimed. “I disagree with some of the things they’re saying and some of the things they’re saying are absolutely ridiculous and abysmal.”

Earlier this week, the group announced that it was winding down its policy operations and letting go of its director amid pressure from the Trump campaign.

But Harris — who has called Project 2025 a “plan to return America to a dark past” — is not moving on.

"This is his agenda, written by his allies, for Donald Trump to inflict on our country," Harris spokesperson Julie Chavez Rodriguez said Tuesday. "Hiding the 920-page blueprint from the American people doesn't make it less real — in fact, it should make voters more concerned about what else Trump and his allies are hiding."