How long will the Kamala Harris honeymoon in the polls against Donald Trump last?

It is back to being a margin-of-error race for the White House.

Former President Trump saw his edge over President Biden expand in the wake of last month's disastrous debate performance by Biden, as calls grew louder from within his own party for the president to drop out of the race.

However, in the eight days since Biden ended his re-election bid, and Vice President Kamala Harris quickly consolidated party support and became the Democrats' presumptive 2024 nominee, polls indicate it is once again a margin-of-error race.

More importantly, it is all tied up again in the battleground states that will likely decide the outcome of the presidential election. Fox News polls conducted after Biden's blockbuster announcement in three of the seven crucial states - Michigan, Pennsylvania, and Wisconsin - indicated Trump and Harris all knotted up.

WHAT THE LATEST FOX NEWS POLLING IN THE KEY BATTLEGROUNDS SHOWS 

Democratic presidential candidate Vice President Kamala Harris speaks at West Allis Central High School during her first campaign rally in Milwaukee on July 23, 2024. (KAMIL KRZACZYNSKI/AFP via Getty Images)

Additionally, in Minnesota and New Hampshire - where Republicans have not won a presidential election in decades, but recent polls indicated Trump was very competitive with Biden - the latest surveys indicate the Democrats re-establishing single digit leads with Harris at the top of the ticket.

2024 SHOWDOWN: TRUMP QUICKLY MOVES TO TRY AND DEFINE HARRIS 

Veteran GOP pollster Tony Fabrizio, who polls for the Trump campaign, predicted it last Tuesday as he pointed to what he called the "Harris Honeymoon."

"We will start to see public polling – particularly national public polls – where Harris is gaining on or even leading President Trump," Fabrizio wrote in a campaign memo. 

Republican presidential candidate former President Trump dances as he wraps up a campaign rally on Saturday, July 27, 2024, in St. Cloud, Minnesota. (AP Photo/Alex Brandon)

"The Democrats and the MSM [main stream media] will try and tout these polls as proof that the race has changed. But the fundamentals of the race stay the same. The Democrats deposing one Nominee for another does NOT change voters discontent over the economy, inflation, crime, the open border, housing costs not to mention concern over two foreign wars," Fabrizio argued.

THE STATE OF THE RACE WITH 100 DAYS TO GO UNTIL THE NOVEMBER ELECTION

He predicted that "before long, Harris’ ‘honeymoon’ will end and voters will refocus on her role as Biden’s partner and co-pilot. As importantly, voters will also learn about Harris’ dangerously liberal record before becoming Biden’s partner."

"While the public polls may change in the short run and she may consolidate a bit more of the Democrat base, Harris can’t change who she is or what she’s done," Fabrizio emphasized.

Vice President Kamala Harris and former President Trump. (Getty Images)

However, veteran Democratic pollster Chris Anderson says it is too soon to make predictions.

"Time will tell, but I’m not even sure she has seen her bump yet. It’s only been a week, so the reality that Harris is the nominee is still settling in, and campaign lines are still being drawn," said Anderson, a member of the Fox News Election Decision Team and the Democratic partner on the Fox News Poll.

Anderson noted that "soon [Harris} will make her VP pick, then there’s the convention. So she has an on-ramp to keep dominating new cycles. So sure, maybe the polls now reflect a bump that will quickly dissipate. Or maybe they are the start of a trend."

Get the latest updates from the 2024 campaign trail, exclusive interviews and more at our Fox News Digital election hub.