WASHINGTON — Backers of a Boston 2024 Olympics have downplayed the need for public money but, based on past budgets and security needs, the city would likely need at least a billion dollars in federal taxpayer support — and perhaps far more.
Supporters acknowledge they will have to mount a significant lobbying effort to persuade Congress, wary of government spending, to support the price tag. Early reaction in Congress is mixed, and some fiscal conservatives appear to be skeptical.
“They made their bid. They should pay for it,” said Representative Darrell Issa, a California Republican.
Local backers’ promise not to use taxpayers’ dollars refers to the operating budget of $4.5 billion. But that does not include security, a formidable federal cost.
Federal dollars also would be needed to cover infrastructure projects — such as the Somerville extension of the MBTA’s Green Line — although the Boston leaders say those costs would occur even without an Olympic bid.
“It’s the whole nation ponying up, I don’t see any way around it,” said Mark Dyreson, a sports historian and professor at Penn State University. “The Games are larger and the world is a different place than 2002 [Salt Lake City Olympics]. I imagine the security costs are going to be in the multiple billions of dollars.”
Officials have not released estimates for such costs. But security for the most recent Summer Games, the 2012 London Olympics, totaled $1.6 billion.
Mitt Romney, a former Massachusetts governor, in his book “Turnaround” devoted an entire chapter to the extensive lobbying efforts needed to pull federal funding for the 2002 Salt Lake City Olympics, which he oversaw. Federal support started at $200 million but stretched to about $600 million, he said.
Romney’s number is far too low, according to outside estimates. A 2000 Government Accountability Office report estimated total federal costs for the 2002 Games would reach $1.3 billion. A Sports Illustrated investigation in late 2001 placed the federal cost at about $1.5 billion.
At least 24 federal agencies reported spending money on the 1984 Games in Los Angeles, 1996 Games in Atlanta, and the 2002 Games in Salt Lake City, according to the GAO report.
Dan O’Connell, president of Boston 2024, the nonprofit spearheading the effort to win the Games, said organizers have modest expectations for federal dollars but will try to secure as much as they can.
“We can’t count on it,” he said, referring to the overall level of federal spending that went to Salt Lake City. “We are hopeful and will be very pleased if it does occur.”
O’Connell said he has yet to fully assess lobbying efforts but plans to seek further advice from the state’s congressional delegation – including Representative Michael Capuano, the Somerville Democrat who sits on the transportation committee – on finding other sources of federal money.
That will be crucial in the next months as Congress considers a new transportation bill.
Over the years the total cost of the Olympics has grown, as governments poured billions into new buildings or overhauled parts of their municipalities. Beijing spent around $40 billion on its 2008 Olympic production and Russia tossed out $50 billion for its splendor last February.
The International Olympic Committee hopes to tone down the over-the-top spending in future ceremonies. But at the very least, the Department of Homeland Security would need to designate the Boston Olympics a “National Special Security Event,” which puts the Secret Service in charge of security. Congress would be expected to authorize funding for the extra safety measures.
O’Connell thinks Congress will approve a security designation — as it did during the 2004 Democratic National Convention in Boston — and provide funding for personnel, equipment, and technology.
The United States Olympics Committee must submit a preliminary bid by September 2015 that will outline some of its spending plans.
O’Connell said the proposal does not depend on the federal government approving new transportation spending. Instead, it relies on projects already approved at the state and federal level, along with the approximately $1 billion a year the state gets in federal transportation money through a formula to pay for them.
The federal government already has approved $1 billion for the Green Line extension to Tufts University, a venue that would be used for games. Other improvements, such as new subway cars for the MBTA’s Red Line and Orange Line, also have been ordered.
Even amid congressional skepticism, Boston may find some allies.
Representative Jason Chaffetz, the Utah Republican who replaced Issa this year as House Oversight Committee chairman, said the investment would prove to be worthwhile.
“I’m a conservative Republican and I’m going to fight for it because most of those dollars are going to go to national security and transportation and infrastructure,” he said. “The economic benefit long term is unparalleled.”
Boston Mayor Martin J. Walsh said that it’s still early to say how much the city could depend on federal support but that Capuano and Representative Stephen Lynch, Democrat of South Boston, may play key roles. Like others involved, Walsh pointed to security and transportation but said the city would not push for projects that are not already in the pipeline. “If the Olympics will give us that little bit of an edge, that would be great,” he said.
Even some in the Massachusetts delegation are unsure how much Congress will offer up.
“I don’t anticipate there is going to be any federal bonanza coming out of this,” said Representative William Keating, a Bourne Democrat. “Clearly, on security matters that is a basic obligation that we share as Americans.”
Lynch hopes to organize a meeting with the delegation and Walsh in coming days to discuss how they can help. He and Walsh have texted back and forth about “the whole security apparatus that would be necessary,” he said.