A double-digit increase in popularity, rising Democratic enthusiasm and an early edge for representing "change" have vaulted Vice President Kamala Harris forward and reshuffled the 2024 presidential contest, according to a new national NBC News poll.

With just over six weeks until Election Day, the poll finds Harris with a 5-point lead over former President Donald Trump among registered voters, 49% to 44%. While that result is within the margin of error, it's a clear shift from July's poll, when Trump was ahead by 2 points before President Joe Biden's exit.

But the transformation in the presidential contest goes well beyond the horse race. For starters, Harris' favorability has jumped 16 points since July, the largest increase for any politician in NBC News polling since then-President George W. Bush's standing surged after the 9/11 terrorist attacks.

Harris also holds the advantage over Trump on being seen as competent and effective, as well as on having the mental and physical health to be president — a reversal from Trump's leads on those qualities when he was matched up against Biden.

And in a contest between a sitting vice president and an ex-president, featuring an electorate that overwhelmingly thinks the U.S. is "on the wrong track," Harris has the upper hand on which candidate better represents change and which candidate can get the country headed in the right direction.

"In July, there was a stiff breeze heading directly at President Biden and obscuring a clear path to victory. Today, the winds have turned in Kamala Harris' favor," said Jeff Horwitt of Hart Research Associates, the Democratic pollster who conducted this survey with Republican pollster Bill McInturff of Public Opinion Strategies.

Still, Trump holds important advantages on the economy and inflation, although those leads are smaller than they were when Biden was still in the contest. Two-thirds of voters say their family income is falling behind the cost of living, and voters ranked the cost of living as their top concern in the election.

What's more, the poll shows that some of Trump's erosion has come from Republicans who aren't die-hard supporters of the former president — but who could come back home to him, like they did in 2016 and 2020.

"We have seen this movie before," said McInturff. "They can get squishy on Trump, and then in the end they come back and they vote the way they're going to vote on a Republican-versus-Democrat preference for Congress."

Overall, the 2024 presidential race looks a lot like it did four years ago, both pollsters agree, with the Democratic nominee more popular than the Republican candidate, the electorate still deeply polarized, and the final result unclear.

"All of this movement to Harris essentially returns the race to where it was in 2020 at the end of the campaign: a very close election," Horwitt said.

This brand-new NBC News poll, conducted Sept. 13-17, comes after a momentous two months in American politics, including Biden's withdrawal from the 2024 race on July 21, two party conventions, two vice-presidential selections, an assassination attempt on Trump in July and another apparent attempt two months later, and the first (and perhaps only) debate between Trump and Harris.

In the first NBC News poll since those events, Harris gets support from 49% of registered voters in the head-to-head test against Trump, who gets 44%. Another 7% either pick another candidate, say they're unsure or say they won't vote.

In an expanded ballot with third-party candidates, Harris leads Trump by 6 points, 47% to 41% — with Robert F. Kennedy Jr. at 2%, Jill Stein at 2% and Libertarian Chase Oliver at 1%. (Respondents were only able to pick from the major third-party candidates who will actually appear on the ballot in their states.)

Both ways of testing the race represent a change from July's poll, when Trump was narrowly ahead of Biden by 2 points on the head-to-head ballot test and by 3 points on the expanded ballot test. The September results are the Democratic ticket's best performance in the poll since the summer of 2023.

In the current head-to-head matchup, Harris holds the advantage among Black voters (85%-7%), voters ages 18-34 (57%-34%), women (58%-37%), white voters with college degrees (59%-38%) and independents (43%-35%).

All of these advantages are larger for Harris than Biden had enjoyed when he was still in the race, except among independents, where Harris' 8-point edge is almost identical to Biden's advantage in July.

Trump, meanwhile, is ahead among men (52%-40%), white voters (52%-43%) and white voters without college degrees (61%-33%).

Seventy-one percent of all voters say their minds are made up, while 11% say they might change their vote — a shift from April, when 26% said they could still change their mind.

The NBC News poll also tests Harris and Trump on 13 different issues and presidential qualities.

Harris' best results are on protecting immigrant rights (where she has a 28-point lead over Trump), abortion (+21 points), having the necessary mental and physical health to be president (+20 points), having the right temperament to be president (+16 points) and representing change (+9 points).

By comparison, Trump's biggest leads are on securing the border (+21), the economy (+9) and dealing with the cost of living (+8).

Those current Trump advantages, however, are all down from when Biden was still in the race. When NBC News put those questions to voters about Trump and Biden in January, Trump led the president by 35 points on the issue of securing the border and controlling immigration and by 22 points on dealing with the economy.

In April, voters gave Trump a 22-point edge over Biden on dealing with inflation and the cost of living, too.

Beyond those issues and qualities, what also stands out in the poll is Harris' increased popularity since her elevation to the top of the Democratic ticket.

In July, 32% of registered voters had a positive view of Harris, versus 50% who saw her in a negative light (-18 net rating) — almost identical to Biden's rating.

But in this new poll, Harris is now at 48% positive, 45% negative (+3).

No major-party presidential candidate in the 35-year history of the NBC News poll has seen this kind of jump in popularity in an election.

And the only increases that are greater than Harris' in successive NBC News polls are George W. Bush's leap after 9/11 (when his positive number increased nearly 30 points); then-President George H.W. Bush's jump in popularity after the first Gulf War (when his positive number increased by 24 points); and independent Ross Perot, who got a 23-point jump when he re-entered the 1992 presidential race after previously dropping out.

By contrast, Trump's net rating in the new poll is essentially unchanged from July — 40% positive, 53% negative (-13).

Despite that improvement for Harris, the poll contains warning signs for Democrats. For one thing, inflation and the cost of living remain voters' top issue. And 66% of voters say their family's income is falling behind the cost of living.

In addition, while Harris leads Trump on "change," a separate question shows a potential vulnerability in being tied to Biden's presidency: 40% of voters say they're more concerned that Harris will continue the same approach as Biden.

That's compared with 39% who are more concerned that Trump will continue the same approach as his first term as president; 18% say neither is a concern.

Meanwhile, 65% of voters say the country is on the wrong track, compared to just 28% who say it's heading in the right direction. Though the wrong-track percentage is smaller than it's been during most of the Biden-Harris administration, the sour outlook closely mirrors how voters saw things when they decided to change the party in the White House in 2016 and 2020.

And while the share of Democrats expressing high interest in the election — registering either a "9" or "10" on a 10-point scale — has increased since July, young voters remain at a low level of interest compared to recent presidential elections.

On the recent debate between Harris and Trump, 29% said the Sept. 10 showdown made them more likely to support Harris, versus 12% who said it made them more likely to back Trump; 57% said it made no difference.

In the battle for control of Congress, 48% of registered voters prefer a Democratic-controlled Congress, compared with 46% who want Republicans in charge. (That's essentially unchanged from July, when it was 47% Democratic, 46% Republican.)

And on Project 2025 — the conservative policy blueprint with ties to former Trump administration officials, which Democrats have featured in their campaign — a whopping 57% of voters have a negative view of it, versus just 4% who see it in a positive light.

The national NBC News poll was conducted Sept. 13-17 of 1,000 registered voters — 870 of whom were reached via cellphone — and it has an overall margin of error of plus or minus 3.1 percentage points.