AMNA NAWAZ: In the final sprint to Election Day, more than 12 million votes have already been cast nationwide.

That includes more than 60-5,000 in Philadelphia, a city in the center of a usual presidential battleground state.

The city's vote processes have drawn the ire of President Trump for more than a decade.

In partnership with the Pulitzer Center, Lisa Desjardins takes a closer look at how officials in Philadelphia prepare for voting.

LISA DESJARDINS: Inside this warehouse in Northeast Philadelphia, workers are firing up the machines and paper that run the democratic process.

LISA DEELEY (D), Philadelphia City Commissioner: These are what we call election activity boxes.

So this box will have in it election materials for every division in the city.

LISA DESJARDINS: They hold poll books, rule books, posters, and pens, everything the city's 1,700 precincts need.

Omar Sabir chairs the city's commissioner's board and says the preparations are working.

Mr.

Chairman, how ready do you feel for this election this year?

OMAR SABIR, Chair, Philadelphia City Commissioners: Born ready.

LISA DESJARDINS: Philadelphia's three elected commissioners, two Democrats and a Republican, run elections in Pennsylvania's largest city.

Democrat Lisa Deeley and Republican Seth Bluestein say party allegiance does not factor into the job.

LISA DEELEY: I would characterize the work that we do more as nonpartisan than bipartisan.

Quite honestly, our job is to be umpires, to call balls and strikes.

SETH BLUESTEIN (R), Philadelphia City Commissioner: Running elections in Philadelphia doesn't require democratic values or Republican values.

It requires American values.

DONALD TRUMP, President of the United States: Bad things happen in Philadelphia, bad things.

LISA DESJARDINS: President Trump has singled out the city in every campaign since he was candidate Trump in 2016.

Two days after the 2020 election, as the counting of Philadelphia's mail ballots cut into his lead in Pennsylvania, he lashed out.

DONALD TRUMP: Detroit and Philadelphia, known as two of the most corrupt political places anywhere in our country.

SETH BLUESTEIN: Both Commissioner Deeley and myself were here in 2020, and we saw the danger of the type of rhetoric and what it could possibly lead through.

We have both received death threats and harassment.

LISA DEELEY: I'd never imagined that I would be at the Convention Center during a global pandemic with protesters on both sides.

I had to leave my home and go live in a hotel.

LISA DESJARDINS: Then again, on Election Day 2024, Trump posted there was -- quote -- "massive cheating' in the city, though city officials said there was no substantive fraud complaints.

DONALD TRUMP: Take a look at Pennsylvania.

Take a look at Philadelphia.

LISA DESJARDINS: Since returning to the White House, Trump has said the federal government should step in.

DONALD TRUMP: The federal government should get involved.

LISA DESJARDINS: He's repeatedly claimed without evidence that mail-in voting is rife with fraud, and he's pushed for federal legislation to overhaul elections.

This month, he posted on social media that results in Philadelphia "will often take weeks to rig."

SETH BLUESTEIN: We have the receipts to show that there's not massive cheating in Philadelphia elections, quite literally.

LISA DESJARDINS: How safe is mail-in voting?

What is the chance of fraud?

LISA DEELEY: Mail voting is safe and it's trusted.

This whole vote-by-mail rhetoric, again, dangerous.

LISA DESJARDINS: While there have been a handful of prosecuted cases of fraud in Philadelphia, the largest centered on some four dozen votes.

And there's been no widespread documented fraud in a presidential general election.

But convincing Republicans of that when the leader of their party says otherwise is a challenge for Bluestein.

SETH BLUESTEIN: I have a lot of interactions with local Philadelphia Republicans.

And part of my job is to help them have confidence in how our elections -- how our elections are run.

LISA DESJARDINS: And how hard is that right now?

SETH BLUESTEIN: Well, it's about building trust, right?

So it's about them having confidence in the work that we're doing so that they can say, you know what, I hear what the president is saying, but I know Seth.

LISA DESJARDINS: Counting the vote does take time.

Bluestein says the reason is written into state law.

SETH BLUESTEIN: In Pennsylvania, we can't start the pre-canvass until election morning, when the polls open at 7:00 a.m.

LISA DESJARDINS: Meaning you can't open the ballots.

SETH BLUESTEIN: We can't even review the outer envelopes.

We can't open the envelopes.

We can't get the ballots ready to be counted.

LISA DESJARDINS: By law.

SETH BLUESTEIN: By law.

LISA DESJARDINS: Every mail ballot comes sealed inside two envelopes.

in 2020, opening and processing the city's roughly 375,000 mail ballots meant more than a million pieces of paper.

The count ran until the Saturday after Election Day.

LISA DEELEY: We will never sacrifice accuracy for speed, and we never have.

And since 2020, we have only gotten better.

LISA DESJARDINS: This year's ballots are already being mailed back.

They will wait in a locked cage until Election Day morning, when processing starts.

Officials hope to be done counting by midday Wednesday.

But a specific 2026 worry is new growing pressure from Washington.

DONALD TRUMP: Cheating on mail-in voting is legendary.

It's horrible what's gone on.

LISA DESJARDINS: An executive order signed by Trump in March would have restricted whom the Postal Service could deliver mail ballots to.

The Supreme Court blocked it from taking effect for the midterms.

Trump's same order directs the attorney general to investigate and potentially prosecute state and local officials who issue ballots to ineligible people.

SETH BLUESTEIN: I'm not concerned.

I haven't given it one second of thought.

I don't think it's a realistic threat.

LISA DEELEY: I can't worry about what he says he's going to do to me.

LISA DESJARDINS: Is it fair to say, when you started, this was kind of a boring job?

LISA DEELEY: It was like a wedding planner.

I mean, basically, you had an election, you rolled out the voting machines, people came, they voted, shut them down.

You went back, took everything apart, and six months later, you rolled it back out again.

And now I have to worry about if somebody -- like, might the president of the United States press and -- like, having me brought up on charges for doing my job?

Like, I can't.

LISA DESJARDINS: The president and his administration have also sent mixed messages about whether federal agents will be dispatched to polling places on Election Day.

SETH BLUESTEIN: Pennsylvania law does not allow for officers or federal agents to be within 100 feet of polling places.

So, right there, that is something that I don't foresee happening in any real way in Philadelphia.

LISA DESJARDINS: Is there a plan if something like that happens?

SETH BLUESTEIN: There is a plan that we have worked with our city's law department on to be responsive if there are any problems on Election Day.

And that's not just limited to federal involvement.

It's incumbent upon elections officials like ourselves to think through every possible scenario that can occur and be prepared for them, even if they're not likely.

LISA DESJARDINS: President Trump's attacks on you and other cities' elections infrastructure, do you see it as more of a distraction or do you see it as dangerous?

LISA DEELEY: It's both a distraction and dangerous.

It's both of those things.

It's dangerous, inasmuch as people are losing confidence in our very foundation of voting.

And that is something that I worry is going to take decades to heal.

LISA DESJARDINS: Their advice for people who doubt the process?

LISA DEELEY: If you don't trust the system or you have questions about it, get involved.

Become a poll worker.

Go see firsthand how elections work in Philadelphia.

We always need poll workers.

Sign up.

MAN: They are entitled to the results of the election.

LISA DESJARDINS: That's exactly what 7,200 people have already done, a little short of the 8,000 the city hopes to have in place.

The poll workers attend training sessions, all in preparation for a long and grueling Election Day that begins at 6:00 a.m.

and sometimes runs past 9:00 p.m.

SHANNA FIELDS, Office of the Philadelphia City Commissioners: We really need willing participants who really will care about democracy and care about the work that we do.

LISA DESJARDINS: Shanna Fields oversees poll worker training for the city.

SHANNA FIELDS: Some of them even have my personal cell number, because I want to make sure that they're safe.

We're like 911 for them.

LISA DESJARDINS: Back at the warehouse, hundreds of voting machines are lined up, ready to be sent out to polling locations across the city.

When the polls close, the results come back here to be combined and tallied.

Since voting machines have no Internet connection, the counts are transferred by secure compact discs to another computer to be released to the public.

SETH BLUESTEIN: I want every voter to have the confidence in our election system that I have.

And that's what we're going to continue to do, is to help them have that confidence.

LISA DESJARDINS: After it's over, the count is audited and their work will begin almost immediately to prepare for the next election.

For the "PBS News Hour," I'm Lisa Desjardins in Philadelphia.