Harris enjoys unparalleled momentum, but her critics doubt it will last

Vice President Kamala Harris’ presidential campaign is surging with unprecedented speed as she eclipses fundraising records, gains popularity and secures critical endorsements.

Within a week of President Biden’s withdrawal from the race, Ms. Harris secured the Democratic Party nomination and closed the polling gap with former President Donald Trump, the Republican Party nominee.

Democrats who were disinterested in Mr. Biden have shown enthusiastic hope that she will keep the White House and help the party take full control of Congress.

The Democrats’ late-in-the-race substitution forced Mr. Trump and his allies to pivot to new lines of attack and adjust their strategy in battleground states.

Ms. Harris’ rapid ascent was further boosted Friday with an endorsement from former President Barack Obama and first lady Michelle Obama.

Republicans predict that the Harris campaign will soon crash. They dismiss her burst of momentum as an expected “honeymoon” now that 81-year-old Mr. Biden and his cognitive struggles are in the rearview mirror.

“Kamala Harris’ surge is artificial and will not last once voters start remembering her record. Right now, Americans are excited that Joe Biden is off the ballot, and that excitement is translating into a minor surge for Harris,” Republican Party strategist James Keady said.

Democrats say the momentum is real and Ms. Harris has yet to peak. They predict she will soon zoom past Mr. Trump in the polls.

“We are seeing organizing not just in our party, but in our country that we’ve never seen before,” said Antjuan Seawright, a Democratic Party strategist. “There were voters who just weren’t ready to commit, and I think Kamala Harris gives them a reason to show up.”

The only way Ms. Harris can maintain her momentum is if Democrats’ enthusiasm for her spreads to independent voters in swing states. That remains to be seen. Polls show the race tightening in several battleground states, but Ms. Harris hasn’t overtaken Mr. Trump.

An NPR/PBS News/Marist poll found Mr. Trump leading Ms. Harris by 1 percentage point (46% to 45%). It also revealed that Mr. Trump is well ahead with independent women. The survey found that 46% of independent voters would pick Mr. Trump in a matchup against Ms. Harris and 32% would back the vice president. Among independent female voters, 43% said they prefer Mr. Trump and 29% said they would back Ms. Harris.

An Emerson College swing-state poll showed Mr. Trump kept his lead in four of five battleground states, but he is ahead by smaller margins than he was against Mr. Biden.

• In Michigan, Mr. Trump leads Ms. Harris by 1 point (46% to 45%) compared with his 3-point lead against Mr. Biden.

• In Wisconsin, Mr. Trump and Ms. Harris are tied at 47%. Mr. Trump led Mr. Biden in the state by 5 points.

• In Georgia, Mr. Trump is up by 2 points (48% to 46%), after leading Mr. Biden by 6 points.

• In Arizona, Mr. Trump leads by 5 points (49% to 44), but he was up by 7 points before Mr. Biden dropped out.

• In Pennsylvania, Mr. Trump is ahead by 2 points (48% to 46%), compared with a 5-point lead he held over Mr. Biden.

Republicans said they expect Ms. Harris’ gains to recede after her campaign’s initial rollout. She owns the same policies and issues that made Mr. Biden a weak candidate in the eyes of the electorate, they said, such as the border chaos and high inflation.

“The No. 1 issue is inflation, and she isn’t going to change that because she’s as responsible for inflation as Joe Biden. This was always going to be a tight race, but I expect this sugar high is going to turn into a slump after Labor Day and she comes back to earth when voters find out who the real Kamala Harris is,” said Ford O’Connell, a Republican Party strategist.

Mr. Seawright sees it differently. He said Ms. Harris will surpass Mr. Trump when independent voters see her spin on Democratic policies.

“The policies she stands for are the same policies supported by independent thinkers and independent voters from reproductive freedom to the war in Gaza,” he said. “She is an electrifying candidate. We’ve never seen this type of energy before.”

Ms. Harris has plenty of encouraging signs. She has erased Mr. Trump’s lead with voters ages 18 to 34 and leaped far ahead of him. An Axios/Generation Lab poll found that 60% of Gen Z voters and younger millennials picked Ms. Harris and 40% went for Mr. Trump. The same poll from earlier in the race found Mr. Trump with a sizable lead over Mr. Biden (53% to 47%) among young voters.

A New York Times/Siena College poll showed Democrats gaining 11 points among voters younger than 30 since Ms. Harris topped the ticket.

Again, Republicans dismiss those gains as an example of an early peak for Ms. Harris.

“She’s taking the lead with younger voters right now. However, after her extreme liberal policies are shown, her numbers will come back to earth,” Mr. Keady said.

Ms. Harris also cut into Mr. Trump’s support from Black and Hispanic voters. Although Mr. Biden led Mr. Trump in those two key voting blocs, the former president was on pace to capture as much as 20% of the Black vote, the most for a Republican candidate since Richard Nixon in 1960. A post-Biden dropout poll by CNN showed Democrats gaining 7 percentage points with Black voters and 6 points with Hispanic voters.

All three groups were among the most troubling for Mr. Biden, who was polling historically poorly with minorities, even though they have voted reliably Democratic for decades.

One ominous sign for Ms. Harris is her favorability rating, which has risen 10 points since February, according to the New York Times/Siena College poll. A CNN poll showed that Ms. Harris has her highest favorability rating since 2021.

Those numbers were far from spectacular. Even with the 10-point improvement, Ms. Harris has a 39% favorable rating and a 52% unfavorable rating. Despite her campaign’s momentum, voters have a more negative than favorable view of her.

Mr. Trump, meanwhile, is improving his image, but his favorability also remains underwater. The CNN poll found that Mr. Trump has a rating of 43% favorable, his highest since 2021, and 55% unfavorable.