The city that made Donald Trump a billionaire — and laughed at him through decades as a boastful businessman whose marriages and divorces were tabloid fodder — finds itself at his mercy.

More than four of five New Yorkers voted against the brash Queens-born Republican. If he chooses to punish the most populous U.S. city, it wouldn't be difficult. More than 10 percent of its $80 billion yearly budget comes from the federal government. Trump's plan to dismantle the Affordable Care Act could cost the city billions of dollars in Medicaid reimbursement that would destroy its public hospitals, Mayor Bill de Blasio says.

De Blasio, a Democrat up for re-election this year, cited such fears at a U.S. Conference of Mayors meeting in Washington last Wednesday in an effort to organize bipartisan opposition to Trump's policies. On the eve of the inauguration of the new president, de Blasio joined several celebrities and thousands of demonstrators at a protest at Trump International Hotel & Tower on Manhattan's Central Park West.

"There's a host of very specific things that I've laid out that are quintessential to stopping the extreme impulses of the Trump administration and that's the plan we're working on right now," de Blasio said during a news conference Tuesday.

The 55-year-old mayor says Trump's espoused goals of deregulating Wall Street, cutting taxes, encouraging charter schools, cracking down on undocumented immigrants and repealing the health care law known as Obamacare will hurt New Yorkers and benefit only the rich.

Trump's supporters, though, say Republican control of the White House and Congress presents an opportunity to push economic growth and benefit all of the city's residents.

"The idea that Trump will be bad for New York, I don't see that happening at all," said Aaron Renn, a senior fellow at the Manhattan Institute, a business-funded nonprofit think tank favoring low taxes and reduced entitlement spending. "This is Trump's home. He has huge investments here. Why would he want to harm the city that he loves?"

Repeal of Obamacare could cause 1.6 million New Yorkers to lose health insurance, leading to the collapse of the city's system of 11 public hospitals and dozens of neighborhood clinics, the mayor has said. The system already faces a $2 billion deficit over the next several years, and more federal and state support is now less likely. To blunt the momentum for repeal, city workers and volunteers have contacted 45,000 uninsured New Yorkers to enroll as many as possible before the new administration can act.

"A reduction of services and access to insurance of this magnitude will certainly translate into unnecessary deaths," Stan Brezenoff, president of the agency that runs New York's public hospitals, said in an interview.

Such talk presents "a doomsday scenario for entirely understandable political reasons," said Paul Howard, who focuses on health care policy at the Manhattan Institute. "I find it highly unlikely Republicans would walk into the trap of yanking coverage out from 20 million people who are enrolled now."

Neither Trump nor Republican congressional leaders have presented a detailed replacement plan.

New York Gov. Andrew Cuomo has predicted that Trump's policies would blow a $3.7 billion hole in the $162 billion state budget, and cause almost 3 million to lose their health insurance. On Wednesday, the two met inside midtown Manhattan's Trump Tower. Afterward, Cuomo expressed hope that Trump would help New York revamp its airports and transit infrastructure. He said he also warned about the consequences of scrapping Obamacare.

"He is a New Yorker, and my sense is that he understood exactly what I was saying and the magnitude of what I was saying," Cuomo said.

Trump Tower, where the president-elect lives and has his international corporate headquarters, has itself become a potential point of contention with the presence of metal blockades, armed guards and crowds of tourists and demonstrators. A city request for $35 million in federal reimbursement to cover security costs between Trump's election and his inauguration was rebuffed last month, when a proposed Republican congressional spending plan included just $7 million.

The mayor also warned about the consequences for cities in the event the Republican Congress and Trump enact tax cuts for wealthy individuals and corporations.

"Where is the federal government going to compensate for all the lost revenue?" de Blasio asked during a news conference last month. "Are they going to take away from education? Are they going to take away from mass transit? Are they going to take away from affordable housing?"

De Blasio's view doesn't consider how much tax cuts will stimulate the economy, said Edward Cox, chairman of New York's Republican State Committee, a backer of Trump's candidacy.

"I expect us to see business tax cuts that will help small companies find the money to hire more workers and stimulate the city's economy in an unprecedented way," Cox said.

Cox's support is a reversal from three years ago, when he refused to back Trump's bid to win the party's gubernatorial nomination without competing in a primary. In February 2014, during a party dinner at the Grand Hyatt Hotel in Manhattan, Trump lashed out at Cox, saying, "He's never won anything, so he doesn't know how to win."

This past April, Trump returned to the hotel — his first Manhattan property, which he rebuilt in 1980 — to bask in applause and profess love for his hometown. At the state party fundraising dinner, an event also attended by several rivals for the Republican nomination, Trump extolled "New York values" as embodying hard work and devotion to family. He invoked the city's response to the Sept. 11 terrorist attacks, saying, "In our darkest moments as a city, we showed the world the very, very best in terms of bravery and heart and soul."

He also reminded the party faithful how during the fiscal crisis of the mid-1970s, another Republican president spurned the city's pleas for federal aid, an injury that he implied he would never commit.

"That was when, and I have to say to Republicans, when Gerald Ford said to New York, 'Drop dead.' Right? Drop dead. That was a killer," Trump said, adding. "We had to do something, because we love New York."