Rust Belt is still at the heart of the 2024 battlefield even without 'Scranton Joe'

"I'm not as worried about it as others may or may not be," one Democrat said.

When President Joe Biden dropped out of the 2024 race, some Democrats feared the party would lose his "Scranton Joe" appeal to Rust Belt voters. But early signs indicate Vice President Kamala Harris, the likeliest candidate to replace him, remains competitive in the key region.

Biden had particularly strong appeal to older voters and white voters without a college degree during his campaign, helping keep hopes alive of drawing an inside straight to reelection through Michigan, Pennsylvania and Wisconsin -- three "blue wall" states that are at the heart of any Democrats' path to victory -- where those voters hold immense sway. Replacing him atop the ticket, the conventional wisdom went, threatened Democrats' footing there

Harris' coalition appears to be that of a more traditional candidate. She has brought young and racially diverse voters back into the fold more than Biden, early polls show, possibly helping her offset any drop-off with other demographics -- a decrease that has not emerged substantially in those surveys.

"It's not going to be her base of voters, but she's not going to get crushed, and that's all that matters," Jim Ananich, the former Democratic leader in the Michigan state Senate, said of older, white voters. "The new rising electorate, the Black and brown community, women, younger voters, she'll make up for it. And I'm saying this is perceived. I don't even know if it's a real deficit."

"I'm not as worried about it as others may or may not be," he added. "I can't tell you today we're going to win, but I don't feel like we're going to lose. I think the election's up in the air."

Fox News polls released last week showed Harris and Trump statistically tied in Michigan, Pennsylvania and Wisconsin, improvements from Biden's standing in the three states.

Fox News' Michigan poll from April showed Biden with 50% support among voters over 65 years old and 31% support among white voters without a college degree. This month, those numbers were 45% and 34%, respectively. Biden took 34% support among men and 31% among white men, with Harris boosting those numbers to 36% and 36%, respectively. Each also got 26% support among self-identified independents.

In Pennsylvania, Biden had 46% support from senior voters and 33% support from white voters without a college degree. Harris matched him among voters 65 years old and up and saw support from white voters without a degree jump to 41% since April. Biden took 40% support among men and 36% support among white men, numbers that jumped to 45% and 42% for Harris, respectively. Biden took 28% support among self-identified independents, a figure that rose to 30% for Harris.

And in Wisconsin, Biden had 49% support from senior voters and 33% support from white voters without a college degree. Those numbers rose to 51% and 40% for Harris this month, respectively. Biden took 40% support among men and 39% support among white men, while Harris took 40% and 41% support, respectively. Independent support for the Democratic ticket rose from 30% for Biden to 35% for Harris.

In all three states, Harris also improved upon Biden's standings with younger and non-white voters.

Taken together, the early data rebuffs the idea of a drop for Harris in a critical region that carried Trump to victory in 2016 and helped spur his loss four years later.

"I'm not going to tell you, 'oh, everything's going to be amazing,' no. But I also don't know that I accept the premise that there's a real problem there," said J.J. Balaban, a Pennsylvania Democratic strategist.

Wisconsin Democratic strategist Ben Nuckels said some are overhyping that there is a problem.

"Honestly, I don't know what that speculation is. She has had a tremendous momentum, she's raising tons of money. I think that there's maybe some beltway politicos that are making some assumptions that perhaps they shouldn't," Nuckels said.

Harris so far is leaving nothing to chance.

One of her first rallies after Biden dropped out was in Milwaukee, and she is anticipated to blitz several swing states next week, likely including in the upper Midwest. Her potential running mate could hail from a key Rust Belt state. And more reinforcements are on the way.

"We already have 600 staff on the ground in the blue wall, and we're adding another 150 to that region in the first two weeks of August," Dan Kannien, the Harris campaign's battleground states director, told reporters Monday.

"The vice president is strong in both the blue wall and in the Sun Belt and we are running hard in both," he added, referencing the reach of states from Arizona and Nevada to Georgia and North Carolina, where Harris is anticipated to perform better than Biden given the more diverse electorate there.

Republicans still aren't sold.

Beyond the poll numbers, GOP strategists told ABC News that Biden's historic appeal in the upper Midwest would be tough to beat. A son of Scranton, Pennsylvania, Biden offered blue collar bona fides, they said, that Harris, who cut her teeth in San Francisco liberal politics, could face headwinds trying to match.

"Joe Biden's background was tailor made for the Rust Belt, given his generation and his issue cluster and where he was from, so it'd be hard to replace him with anyone who has more of a potential for Rust Belt voters," said veteran Pennsylvania GOP strategist Chris Nicholas. "It'd be hard to find a Democrat with more natural appeal to the Rust Belt states."

Republicans also speculated that Harris could be enjoying a sugar high as the result of her whirlwind ascent to the top of Democrats' ticket. But Harris and Trump are engaged in a pitched race to define her, the outcome of which could prove determinative to the vice president's standing.

"She certainly has enthusiasm here. But I think we need to get past the shiny-new-penny stage and get into hardball politics, what her record says, what the Trump attacks will be," said Wisconsin GOP strategist Brandon Scholz. "I don't think you've even seen that scratch the surface."

And there are still issues that offer Trump fertile ground for attacks.

Chief among them is inflation, which Trump had been hammering away on before Biden dropped out and is anticipated to continue to focus on with Harris as his opponent. Former Rep. Mike Bishop, R-Mich., said that line of attack could prove particularly effective with the kinds of blue-collar workers who dominate the Rust Belt amid stubbornly high frustrations over inflation.

"We do have a very blue-collar populace here," Bishop said. "She's going to have to cater to them and prove to them why their lives are better over the past four years and try to put together some kind of plan to show that she can continue that process going forward."

"Most people do consider their pocketbook and their family and their family budget, I think absolutely that's an important issue. I don't know how you can get past that," he added.

Still, Democrats are essentially jubilant over Harris' chances. Biden's chances of reelection were widely perceived to have taken a near-fatal hit after his cataclysmic debate last month, and having a candidate to just make the race competitive again has Democrats feeling the wind at their backs.

"On the ground, things feel great … the momentum has completely flipped," Nuckels said.

"All the polling showed [Biden] was down, all of it," he added. "It was going to be a very, very difficult race, and something major needed to happen in order for him to gain that momentum back. But it was not headed in the right direction."