Former New York mayor Rudolph W. Giuliani walks through the streets of Mexico City under heavy security in 2003 after meeting with police officials to come up with a crime-fighting plan. (Victor Caivano/AP)

Rudolph W. Giuliani branded himself the man who cleaned up New York City, and not long after he left the mayor’s office, he insisted on seeing some of the most dangerous neighborhoods of Mexico City — albeit in an armored convoy with a huge security force — to assess how he could do the same there.

A consortium of Mexican businesses had paid Giuliani’s consulting firm $4.3 million for a comprehensive review of the city’s justice system — including police training, internal affairs and the prison system, said Bernard Kerik, a former New York City police commissioner who helped manage the project.

The work — which Giuliani went on to shop around Latin America — made the politician dubbed “America’s mayor” a wealthy man. He wrote in a 2007 financial disclosure form that the holding company for his business interests was worth $5 million to $25 million.

But the effect Giuliani’s advice had on reducing crime is debatable. And now — as ­President-elect Donald Trump considers whether to appoint him to a Cabinet post — government ethics analysts and even a prominent Republican senator are questioning how Giuliani might be able to set aside financial entanglements with foreign interests should he return to public office.

President-elect Donald Trump meets with former New York mayor Rudolph W. Giuliani in New Jersey on Nov. 20, saying he's a candidate for secretary of state and "other things." (The Washington Post)

“If he were anywhere in the U.S. government,” said Richard Painter, who was chief ethics lawyer for President George W. Bush, “these things would have to stop immediately.”

Kerik said concerns about conflicts are “political garbage.”

“If he wound up taking over State, he’s going to represent the interests” of the United States, Kerik said. “He’s not going to give a damn who he had dealings with in the past.”

Giuliani is perhaps best known for his time as the mayor of New York. He was in office during the terrorist attacks of Sept. 11, 2001, and drew widespread praise for his response. Crime also decreased in the city on his watch, and he has claimed — somewhat dubiously — that his policies drove the decline. Crime in the city was falling before he became mayor, part of a national trend.

When he left office at the end of 2001, Giuliani entered the lucrative world of consulting — forming a company, Giuliani Partners, and a subsidiary, Giuliani Kerik, and using his reputation as a crime fighter to drum up business.

Giuliani’s 2003 Mexico City proposals, which were endorsed by that city’s mayor, were largely the ones that he had implemented in New York — an aggressive approach to petty crime, with increased arrests and stiff fines, police training, and zero tolerance of the graffiti and broken windows that made residents feel unsettled in their communities. The contract led to many more around the world.

Former New York City Mayor Rudy Giuliani (R) is a big fan of Donald Trump – and he said some strange things while campaigning for the Republican nominee. (Peter Stevenson/The Washington Post)

“We’re here to give advice” to a Belgrade mayoral candidate “about economic development and how to organize a program to redevelop Belgrade, make it into a great world city,” Giuliani said in a 2012 interview on Serbian television, reported by CNN. He said his company had worked in Mexico City, Puerto Rico, Colombia and the Middle East.

“My company gets paid for it, I don’t get paid for it,” he said. “That’s what my company does; gets paid for giving advice.”

In some places, Giuliani has been tapped largely to show up and look tough. In Peru in 2011, law-and-order presidential candidate Keiko Fujimori employed him to accompany her on the campaign trail to project a crime-fighting image.

There is no complete public accounting of all of Giuliani’s clients, and it is difficult to assess just how much money he has made — and from whom — through the years. A person with knowledge of Giuliani’s firm’s finances told The Washington Post in 2007 that its staff had quadrupled in its first five years of existence and that it had grossed more than $100 million. Giuliani Safety & Security, a subsidiary of Giuliani Partners, says on its website that it has “affiliations and engagements” in 63 countries across six continents.

Even in places where crime decreased, it is difficult to attribute the drops to Giuliani’s prescriptions. In a 2011 address to Juarez Competitiva, a two-week event designed to showcase the city to the world and transform its image as Mexico’s murder capital, Giuliani “spoke of similarities between New York and Juarez and praised the potential for broken-windows theory in the crime-ridden metropolis,” said Kate Swanson, a professor at San Diego State University.

Studies of the Juarez turnaround, however, attribute it more to government restructuring, business contributions and revitalization of the judicial system.

Assessment is similarly difficult in Mexico City, where Giuliani has said his policies substantially reduced crime. Subsequent studies by academics have assessed that reductions were primarily in heavily policed upper-class neighborhoods and tourist areas, and that Giuliani’s recommendations were ill-suited for societies where as many as half of all workers participate in an informal economy and the greatest fear of many is of the police.

“Given vast inequalities [economically, socially and racially], high levels of police corruption and limited infrastructural resources, zero tolerance in Latin America is often implemented in a way that explicitly targets the poor,” Swanson wrote in a 2013 study.

In Colombia, where Giuliani has been paid for government consultations, and where his recommendations have been followed to some degree in the cities of Medellin, Cali and Bogota, officials attribute a decrease in homicides, if not other forms of crime, at least in part to his methods.

“He came twice and gave me advice on how to be more effective, and how to focus our capabilities,” including law enforcement and the military, “on specific areas or hot spots,” said Juan Carlos Pinzón, Colombia’s defense minister at the time and now its ambassador to the United States.

“I see it as a positive,” Pinzón said.

Giuliani has said on Fox News Channel that his group reduced crime in Cali by 42 percent. Others say that the beginning of the drop predates Giuliani and that it began with innovative social and law enforcement policies adopted by then-Mayor Rodrigo Guerrero, a Harvard-trained epidemiologist.

Asked whether he thought Giuliani’s security work was effective in Mexico City, Kerik said he could not force the implementation of his advice.

“We weren’t paid to manage the city,” he said. “We were paid to tell them what the problems were.”

Kerik left Giuliani’s company in 2004; he was later convicted of tax fraud and lying to the government as he was being vetted for administration posts.

Neither Giuliani nor representatives of the company returned messages seeking comment for this article. Mike DuHaime, who managed Giuliani’s unsuccessful presidential campaign in 2008, said that he did not discount people questioning Giuliani’s work abroad, but that he did not think it would be problematic.

“I also think he’s going to be judged on his totality of public service,” DuHaime said.

Giuliani has entertained speculation that he would take the State Department job. When he was asked at a Wall Street Journal CEO Council meeting Nov. 14 if his title would soon be “secretary,” he said, “One never knows.”

Lawyers specializing in government ethics said Giuliani’s receipt of payments from governments or organizations abroad would not preclude him from serving as secretary of state — although they could present problems at his confirmation hearing or force him to recuse himself from certain issues, depending on how recently he was paid by a foreign entity.

Painter said that federal law would force Giuliani to recuse himself from dealings with any entity that had paid him in the past year, and that he probably would have to rid himself of interests in his company. He also could be forced to disclose his dealings to win Senate confirmation, and — given Republicans’ intense criticism of the foreign entanglements of the Clinton Foundation while Hillary Clinton, Trump’s Democratic challenger, was secretary of state — that might “raise some eyebrows.”

Giuliani, like Clinton, has been rewarded handsomely for paid speeches. He wrote in his 2007 financial disclosure form that he had grossed nearly $12 million from such engagements, earning six-figure sums from businesses including JPMorgan Chase, Merrill Lynch and German shredding company HSM.

Sen. Rand Paul (R-Ky.) has said Giuliani would face a “stiff, uphill climb” to win his support for secretary of state, because of his foreign dealings and his support for the Iraq War.

“I think it is worrisome, some of the ties to foreign governments,” Paul said on CNN. He added later, “Whether or not you have divided loyalty obviously is very important.”

Giuliani’s foreign work has not been limited to Latin America. He gave speeches on behalf of an Iranian dissident group that was once listed as a foreign terrorist organization. The New York Times reported that his company had contracts with the government of Qatar and the Canadian company building the Keystone XL oil pipeline. He also has ties to a company called TriGlobal Strategic Ventures, a venture capital firm focused on Eastern Europe that includes on its advisory board Ara Abramyan, a business executive who it says is a “very close Advisor to the Russian Government’s inner circle including the President and the Prime Minister.”