Shortly before former President Donald Trump's unlikely return to the Democratic stronghold of Albuquerque, New Mexico, on Thursday -- just five days ahead of Election Day, Albuquerque's Democratic Mayor Tim Keller sent a special welcome message for the former president.

"Still waiting for Trump to pay the half million he owes. Maybe he's making a special Halloween delivery to the Duke City? We won't hold our breath," Keller posted on his social media, with a photo of a skeleton sitting at a desk.

Thursday was Trump's first visit to Albuquerque in five years, after officials say he left an unpaid bill of $211,176 in public safety costs from his 2019 rally at the Santa Ana Star Center in Rio Rancho, which is a part of the Albuquerque metropolitan area.

Fast forward five years, the bill has now snowballed into $444,986 including interest over the years, according to the city of Albuquerque.

Albuquerque is just one of many cities where Trump's campaign -- over his three tries for the White House -- has accrued hundreds of thousands of dollars in unpaid bills after holding campaign events, often leaving local governments with hefty sums of unexpected expenses that cause them to go over their budget.

ABC News has spoken with officials from more than a dozen cities and municipalities he has campaigned in over the last few years, where his rallies and events have cost the cities between tens of thousands of dollars to hundreds of thousands of dollars in unreimbursed expenses, including overtime payments for local police officers, fire fighters, EMS and other first responders deployed to guide and protect the crowds Trump's campaign events attract.

The Trump campaign’s lack of payment for such costs continues even as the former president touts his support for law enforcement officers and promises better benefits and work conditions for them, while attacking Vice President Kamala Harris once supporting the Defund the Police movement. 

While Trump isn’t the only political figure whose campaign events produce extra public safety costs for local governments, his visits – which bring thousands to tens of thousands of people to small towns – have often required more public resources than other recent presidential candidates. That, coupled with his unique and long political career of running as a presidential nominee for three consecutive presidential election cycles, has led to the bills piling up.

Trump’s massive rally at the Santa Ana Star Center in the Albuquerque metropolitan area in 2019, for example, caused an “extreme strain on resources” for the city by forcing the city to shut down the downtown area, including the city hall. Police officers, first responders and other city employees who assisted with the rally worked a combined overtime of 1,500 hours that night, according to the mayor’s office.

His office told ABC News it has sent the bills to Trump's residences in New York and to Mar-a-Lago – and that a collection agency is currently working to recover the debt.

Some cities opt to not bill the campaign at all, like Rio Rancho, which ended up with nearly $240,000 in expenses after assisting with Trump's 2019 visit to the Albuquerque metropolitan area. The city's spokesperson said it chose not to seek reimbursement from the Trump campaign because it determined these costs "necessary to ensure the health, safety, and welfare of its citizens."

Similarly, in September, Nassau County opted not to bill the Trump campaign after his massive rally in Long Island cost $1 million in police overtime alone, according to the county’s Minority Office of Budget review, prompting Democratic legislators to file a Federal Election Commission complaint against Republican Nassau County Executive Bruce Blakeman claiming improper use of taxpayer resources for a presidential campaign.

Campaign Legal Center’s senior legal counsel Shanna Ports told ABC News that a state or municipal government can deploy official resources like police officers to a presidential campaign event without being reimbursed by the campaign if those resources are used “solely to ensure the safety of attendees – consistent with how it would respond to any non-campaign event.”

Tens of thousands bills from recent campaign events leave cities in critical battleground states

But numerous other local governments like Green Bay, Wisconsin, and Erie, Pennsylvania, where Trump visited to court key battleground voters, have sought to get reimbursement from the Trump campaign — with little success.

On Wednesday, Trump campaigned in Green Bay, Wisconsin, where his rally in April earlier this year had left the city with more than $33,000 in public safety costs, including roughly $24,100 in police overtime, the city told ABC News.

This was after the Trump campaign in 2016 left the city without more than $9,000 in unpaid bills after a campaign event. Former Secretary of State Hillary Clinton's campaign also has nearly $12,000 in unpaid bills from her rally there in 2016, the city said. The city is still determining total costs incurred from Trump's recent visit.

Vice President Kamala Harris' visit in July cost Green Bay $635 for police deployment, which the Harris campaign had not yet paid as of October, the city's spokesperson told ABC News.

In another battleground state of Pennsylvania, the city of Erie has recently sent an invoice of $63,190 to the Trump campaign for his rally in September but the campaign has yet to respond to the city's request for payment, according to the city's Communications Director Robert Lee.

The campaign already had unpaid bills of more than $35,000 in Erie prior to his September visit, including $5,200 from his rally in July last year and $32,000 from his rally in 2018. Erie's spokesperson also said the city plans to bill the Harris campaign "for still-to-be-determined costs incurred by city police and other departments in relation to her rally last month.

Asked about unpaid bills to local agencies, a Trump campaign official directed questions related to local law enforcement and first responder costs to the U.S. Secret Service.

A spokesperson for the Secret Service in a statement to ABC News acknowledged the lack of mechanism to reimburse local governments for costs incurred from supporting the Secret Service despite a "crucial" role local law enforcement agencies play in the operation.

"In recent discussions with Congressional leaders, we identified this as a critical need, given the essential role our police and public safety partners play," the statement reads. "We are grateful for the additional funding provided in the continuing resolution, and we will continue to work with Congress to advocate for the necessary resources to support the city, county, and state law enforcement agencies that assist us every day."

How cities are finding new ways to ensure payment from campaigns

Like Albuquerque, the city council of El Paso, Texas, has hired a law firm to collect more than half a million dollars in unpaid bills from Trump's rally in 2019, including roughly $470,000 in public safety costs and nearly $99,000 in one-time late fee. The city is still seeking a payment from he campaign, a spokesperson told ABC News.

In Tucson, Arizona, the city decided not to pursue roughly $80,000 in public safety costs incurred from a Trump rally in 2016, nor did it with roughly $40,000 incurred from Bernie Sanders' rally there in that year, as the city determined a legal action could be more costly, the city's spokesperson told ABC News.

Instead, when Trump returned to Tucson in September, the city required the campaign to pay estimated public safety costs in advance along with the facility rental cost – ensuring the campaign's total payment of $145,222 up front, including nearly $116,000 in police department costs.

In Eau Claire, a small town in Wisconsin, Trump's visit in 2016 left the city with more than $47,000 in unpaid bills and Clinton's visit the same year with $6,800 in unpaid bills, contributing to the city's operating budget going over by nearly $62,000 that year.

Eau Claire's budget analyst Corey Lee told ABC News, "Overall, it is a low expense in the grand scheme of things" but added that "ideally, we would want to recover costs for circumstances that are unforeseen or outside of normal city operations."

"But we also have the responsibility of protecting the community regardless of the circumstances," he said.

More recently, Eau Claire has been billing public safety costs through venues instead of directly sending invoices up front to campaigns, to ensure payments from campaigns -- including $4,000 from Sen. JD Vance's visit in September and roughly $16,000 from Harris' visit in August.

Wisconsin mayor: 'We expect to be reimbursed. Or we'd say, 'Don't come'

In Prairie Du Chien, a small town in Wisconsin of just over 5,000 population, Trump's campaign remarks focused on border security and immigration. The event, held at the local high school's arts center in September, left the city with $17,000 in public safety costs.

The campaign paid the local school district ahead of the event for renting out the arts center but didn't have an answer when Prairie du Chien's Mayor Dave Hemmer asked about reimbursements for public safety costs in advance of the event.

"He basically said we typically don't do that. And I said, well, I think that's in polite language – I think that's a bunch of BS," Hemmer said of his conversation with the campaign staffer before the event. Hemmer said he also asked the staffer about reimbursements on the day of the event.

Prairie du Chien's Police Chief Kyle Treynor, who spoke on stage as one of the pre-programming speakers during Trump's visit, told ABC News that the Secret Service advised him to bill the expenses to the campaign if they wanted reimbursement as the service does not reimburse the local police department for these costs.

Treynor said police chiefs of other cities in the Southwest region of Wisconsin that have similarly hosted Trump events have told him they have not gotten reimbursed from the campaign either.

"So I have a lack of anticipation of being paid as well. So we will invoice them and hope that they do the right thing and pay. And if they don't, we'll consider options at that point," he said.

Hemmer, the mayor, said $17,000 is "not going to bankrupt us" but that it's "not a small amount" to Prairie du Chien.

"Honestly, I don't expect to get 100% reimbursement, but I would be happy to get 50% reimbursement. I think that would probably make it a difference," Hemmer said.

"And I've had, we've had a couple of people, local residents, calling, saying, demanding, 'I want to know how much it's cost, and are we going to get reimbursed for that?' And I don't have an answer either way right now, because I don't know what the final cost is," the mayor said.

Hemmer said candidates are welcome to campaign in Prairie du Chien -- but not if they don't pay their bills.

"He's welcome here, but we need to have our bills paid, any expenses incurred by us for him being here, or we don't really want him here," Hemmer said. "And I would say that about, you know about Trump or vice president here, Harris, the same thing, because, like, we are a smaller city and if we incurred expenses like that, we expect to be reimbursed. Or we'd say, 'Don't come.'"