The World Conservation Congress, a major international event next month in Waikiki, may attract President Barack Obama as the opening-day speaker, but local organizers expect far fewer attendees than original estimates, and say they might be up to $1 million short on funding to host the 10-day summit.

Coming to Hawaii Sept. 1-10, the premier conference of the International Union for Conservation of Nature is the state’s highest-profile international meeting since the 2011 Asia-Pacific Economic Cooperation forum. It also will mark the first time the U.S. has hosted the global conference since the organization’s creation in 1948.

Obama is expected to speak at the event’s 90-minute opening ceremony, which will begin at 10 a.m. on Sept. 1. That event, which could attract 4,000 attendees, will be held at the Neal S. Blaisdell Center because the soaring glass walls at the main host site, the Hawai‘i Convention Center, don’t meet the U.S. Secret Service’s security requirements.

“The president’s attendance hasn’t been confirmed yet. At the same time, the White House hasn’t said no,” said Randall Tanaka, executive director of Hawaii’s WCC National Host Committee.

Either way, Tanaka said, event organizers and federal, state and city partners must plan for the highest level of precaution.

“Public safety is our No. 1 concern,” said Maj. Ryan Borges, who oversees HPD’s major events division. “The Honolulu Police Department has worked diligently with our city, state and federal partners. Together, we have developed a comprehensive plan to ensure a safe and enjoyable IUCN experience for our visitors and residents.”

About 300 HPD officers are ready to work with security partners, Borges said. The city also plans to clean up the area around event venues, including enforcement of laws aimed at the homeless. Officials said motorists can expect traffic disruption during the event, and there will be bus stop relocations, closures of parks, parking lots and sidewalks, and other security measure.

City officials said Wednesday that estimated costs for HPD, the Honolulu Fire Department and other city departments are unavailable. However, some departments, including the Department of Facilities Maintenance, have estimated conference costs at more than $72,000. Some city overtime costs will be defrayed through a federal Department of Homeland Security grant, they said.

Tanaka said the city and state will bear more of the costs for this security than it did for APEC, which had federal support due to its status as a National Special Security Event.

“There will be some burden on the state and city. But if we pull this off the way that we’ve planned, we’ll demonstrate that Hawaii is a significant place to hold a world-class global meeting,” he said.

Tanaka said nearly 5,000 delegates are coming from 170 countries, including Cuba and North Korea. About 3,000 friends, family and support staff also are expected, along with 200 registered journalists. Together they could generate up to $62 million in total economic impacts, including $26 million in direct visitor spending and another $3 million in tax collections, he said.

Tanaka said event attendance, which at one time was expected to hit 10,000, was depressed by visa issues and global economic and security concerns.

Even with the delegate shortfall, he said, the event will fill thousands of hotel rooms during what is typically an off season for Hawaii’s tourist industry.

Mufi Hannemann, president and CEO of the Hawaii Lodging & Tourism Association, said industry members closest to the convention center are seeing the greatest gains. Hotels farther from the center aren’t faring as well, he said.

Tanaka said green-certified, lower- to mid-priced hotels were most popular with delegates. Transient vacation units also appear to be garnering a share of business, Hannemann said.

U.S. Sen. Brian Schatz, who helped bring the conference to Hawaii, said it will reinforce the state’s reputation as an ideal location to host high-level international forums. “I can think of no better place than Hawaii to convene world leaders to work towards solving the most pressing global conservation and energy security challenges,” Schatz said.

Hawaii Tourism Authority President and CEO George Szigeti said the conference also will showcase state and visitor industry efforts to protect natural resources and use sustainable practices.

“I’m confident IUCN’s delegates will appreciate the initiatives our state has taken to support the environment and how our visitor industry and businesses live it every day,” Szigeti said. “This is the kind of news that will resonate with conservation-minded travelers wanting to experience destinations that share their views on how society and ecology can co-exist.”

A good return on investment will be important to state taxpayers, who already have spent millions more to host this gathering than for APEC. WCC’s host committee must pay $11.4 million of WCC’s $13.2 million cost. In contrast, APEC’s host committee raised about $5 million for an event that drew more than 15,000 visitors, including 2,000 journalists, and pumped an estimated $120 million into the state’s economy.

“The dollars spent on police services for APEC were considerable. We’ll get stuck with a big bill, but hopefully taxpayers will see some benefits,” said Barry Wallace, executive vice president of hospitality services for Outrigger Enterprises Group.

So far, most of WCC’s support has come from state funds. Former Gov. Neil Abercrombie transferred $4 million from the state’s Special Land Development Fund in 2015. Gov. David Ige asked for another $4 million in special fund money from the state DLNR. HTA gave $1.5 million, which included $690,000 of in-kind fee waivers at the Hawai‘i Convention Center.

Still, Tanaka said, the host committee is about $500,000 to $1 million short.

“It’s crunch time,” Tanaka said. “If someone walks in the door tomorrow with $1 million, we would welcome them. But we’ll be OK. The event is still going to go really well.”

Tanaka said the host committee, which has been fundraising since May 2014, will launch a campaign next week appealing to national conservation groups. Tanaka said organizers also will use cost-saving measures such as cutting transportation and food services based on conference demand.

“We won’t know until mid-conference if our operational costs have exceeded the budget. It depends on what the end product consumes,” Tanaka said.

If costs exceed the budget, Tanaka said Hawaii might have to make up the shortfall. “It could happen, but we are working hard not to have that happen,” he said.