Organizers behind Boston’s bid to host the 2024 Summer Olympics said Friday that it could cost an estimated $4.5 billion to put on the Games, as several lawmakers who attended a closed-door briefing said they came away encouraged by the latest plans.
“I went in skeptical, and came out optimistic,” said Nick Collins, a state representative who chairs the Boston delegation. “If other cities around the world can pull this off, why can’t we?”
Dan O’Connell, president of the Boston 2024 Partnership, said the $4.5 billion pricetag would be offset by $1.2 billion in expected broadcast revenue and large contributions from sponsors.
Collins said organizers assured lawmakers that no public money would be required for construction projects directly related to the event, such as stadiums and housing for the athletes. Legislators, he said, would summarily reject any requests for taxpayers to foot the bill for these basic operations.
“If the private sector isn’t going to pick up those costs, we’re not going to have these Games,” Collins said. “It was made very clear the public was not going to pick up the tab.”
However, O’Connell acknowledged the $4.5-billion figure does not include the cost of public infrastructure, including road and transit improvements.
Collins said substantial improvements to the region’s transportation network are needed regardless of whether Boston is chosen.
“We need to get serious about our infrastructure,” he said.
At Friday’s meeting, the first formal briefing with Boston legislators, the lawmakers raised concerns about cost, traffic, and security, O’Connell said. Some critics have said the city is ill-equipped to handle such a vast and costly undertaking.
Liam Kerr, co-chairman of a group of opponents called No Boston Olympics, said the Games typically go well over budget, siphoning public money from more pressing priorities.
“Bostonians hoping to hear more about improving education and safety should get used to politicians and power players doing photo ops instead,” Kerr said.
After Friday’s meeting, lawmakers stopped short of wholehearted support — and some expressed surprise that Boston has a better chance at being chosen as host than they had believed.
“I learned at the meeting that this is actually a very serious proposal — that Boston is definitely in the running, in the eyes of the Olympic committee,” said State Senator Anthony W. Petruccelli of East Boston. “I’m interested in learning more.”
State Representative Michael J. Moran, of Brighton, was impressed by the plans to have almost all of the Olympic sites in a compact area and accessible by walking or public transit.
“I would think the Olympic committee would be really impressed with how accessible it would be,” he said. “This plan has really come a long way. So now I’m thinking, this might not be wishful thinking, we have a real shot at it.”
Organizers are proposing a compact layout for the games, using the city’s public transportation network to connect the venues and the area’s wealth of college facilities.
Among the ideas: An Olympic stadium could rise out of a dingy industrial stretch beside the expressway near South Boston, with a half-mile boulevard escorting spectators from South Station. Athletes might bunk at an Olympic village by UMass Boston, and beach volleyball could come to Boston Common.
“We would not be able to host the games without university participation at the very highest level,” O’Connell told reporters at the group’s Seaport headquarters.
In June, the US Olympic Committee chose Boston, Los Angeles, San Francisco, and Washington, D.C., as candidates for a potential US bid to host the games. The committee could announce its choice as soon as January.
The International Olympic Committee will choose the host in 2017.
The “compact games” model, with venues concentrated in and around Boston, would rely on temporary and upgraded facilities, with a goal of creating no “white elephants,” or structures that would have no use beyond the Games, O’Connell said.
“It’s a model like London,” he said. “We’re looking for an Olympics where facilities are either temporary or will continue to be used by universities.”
Venues would be located to take advantage of expected transportation upgrades, such as expanded commuter rail and subway service.
“The games will act as a catalyst,” O’Connell said. “We can really upgrade the system as part of this.”
Boston organizers, a private group consisting of prominent Massachusetts businesspeople, have been working since last year on a bid. The group is promising a privately financed Olympics that would rely on public infrastructure improvements.
“We would hope to have a surplus of funds,” he said.
Mayor Martin J. Walsh, who attended the Beacon Hill meeting, described it as positive but preliminary.
“We did speak about some specific proposals, but it’s important to note that this is a very fluid process, and this is just the beginning of a long and robust public dialogue,” he said in a statement.
Still, some details are coming into focus . Boston University and Northeastern University have agreed to provide rooms for the media, O’Connell said, and several colleges would host events. Field hockey would be played at Harvard, while MIT would host archery and fencing. The marathon would end on Charles Street by the Public Garden. Franklin Park would be transformed into an equestrian venue.
The proposal does not include plans for an Olympic Park, O’Connell said. The city itself would fill that role.
Peter Schworm can be reached at firstname.lastname@example.org. Follow him on Twitter @globepete.