“The problem is the workforce,” said Pierre Brajeux, president of the French Federation of Private Security. “Will we have enough guards to properly ensure the security of the Games? We need to hit the accelerator.”

The Olympics organizers, he said, “have struggled to find companies” through four rounds of contract bidding.

An especially tough sell: the job of managing the 104,000 ticketed spectators on the lower banks of the Seine during the floating boat parade of the July 26 Opening Ceremonies. President Emmanuel Macron has said that only in the case of a clear and imminent terrorist threat would the event be modified — contained in the Trocadero Square facing the Eiffel Tower or moved to the Stade de France, the national stadium.

“We didn’t manage to convince the companies for the ceremony,” Paris 2024 security chief Bruno le Ray told Le Monde this past week.

Some private security companies were reluctant to bid because they didn’t want to be liable for contracts they might not be able to fulfill. Even before the Olympics, the sector assessed that it was dealing with a labor shortage of 20,000 people. Although there has been a concerted push to get more people trained and certified, including through an accelerated three-week course funded by France’s unemployment agency and the regional administration, it may not be enough.

Sports Minister Amélie Oudéa-Castéra said in a television interview this past week that the sector needed 8,000 more recruits to ensure full staffing for all the Olympics events in Paris.

Above all, French officials want to limit the vulnerability of the Games — to terrorism, crowd crushes and other security threats. They are also wary of an embarrassment like during the London 2012 Olympics, when a private security company’s failure to deliver on its contract meant that military troops had to be called in to check handbags.

Some officials have shrugged off concerns, saying that more than 20,000 people are newly trained or in the pipeline. By July, they should at least be certified to work at major events — doing bag checks and pat-downs, interacting with crowds, monitoring for suspicious behavior and performing other basic security work.

“There is no failure. We have surpassed the goals that we had set for ourselves,” Marc Guillaume, the chief administrator for the Île-de-France region, said at a news conference on Thursday.

But private security specialists said that while they appreciate the government’s efforts, officials may be overestimating the number of contractors available and underestimating how many contractors will be needed this summer in connection with the Olympics — not just at competition sites but at airports, train stations and department stores.

Brajeux said the Olympics pose a “problem in terms of geography and of timing.”

The Games will take place in late July and August, when about a third of French security contractors are traditionally on vacation. And many of the country’s certified contractors don’t live in the Paris region, where the vast majority of competitions will be held. They may not be keen to spend weeks in the capital without their families, working long shifts in the oppressive Paris heat.

The newly trained people will provide a boost. But they won’t all be hired for the Olympics. Typically, only about 60 percent of those who go through training go on to take private security jobs, according to industry estimates. Moreover, because the training is not Olympics-specific, people getting certified this year may be recruited for the Games — or for construction sites or to replace people leaving the sector.

Brajeux said things could still be turned around. A final recruitment push now aims to attract last-minute candidates, including students. “If there is a big wave of candidates,” he said, “we have the capacity to train them. We have enough training facilities.”

“People think one needs to do karate to work in private security, but that’s not the case,” he said.

Some applicants for Olympics roles have themselves generated security concerns.

Officials have screened only a small portion of the 1 million people they want to assess before the start of the Games. But as of late March, according to Interior Minister Gérald Darmanin, 800 had been excluded from participation, including 15 people who were on national security watch lists.

“There are people who wanted to register to carry the flame, be volunteers at the Olympics, and who clearly did not have good intentions,” Darmanin said.

He noted that officials were also screening everyone holding private security certification “out of precaution,” in case some of them might be asked to help at the Olympics. The Interior Ministry flagged 1,392 of them, including 102 who were on watch lists.

By early April, the total number of people excluded because they were on watch lists appeared to have risen from 117 to 161 people, according to Darmanin: 105 for radical Islam, 35 for the extreme right, 18 from the extreme left and three for foreign interference. Almost all were French nationals.

While those findings could indeed reflect the “possibility of an infiltration” by militant groups such as Islamic State-Khorasan, the Afghanistan and Pakistan arm of the Islamic State, other dynamics may also be at play, cautioned Marc Hecker, a French terrorism researcher.

“The watch lists are pretty big,” he said. Some people may have ended up on them accidentally. Others may have at some point been suspected or convicted of extremism-related crimes but are genuinely trying to reintegrate into the job market.

Brajeux said he was not concerned about the exclusion of the security contractors. “On the contrary, it’s comforting,” he said, noting that fewer than 1 percent of guards were flagged by the authorities. He added that although 280,000 people were screened, “only around 180,000 people really work in this sector. Some have changed profession, others died.”

In addition to French private security, the police and the military, the Paris 2024 security plan includes support from about 50 foreign countries who are expected to send a combined 2,500 officers and an array of equipment.

Darmanin said they will focus on “securing their teams, lending us anti-drug, anti-bomb or anti-weapon dogs, or being in touch with their compatriots.” He added that they may be armed.

Poland said it would be sending soldiers, including dog handlers, focused on explosives detection and counterterrorism. In Rabat this past week, he thanked Morocco for being among those to agree to send law enforcement officers this summer, while a security committee from Qatar visited the gendarmerie headquarters in Paris to plan coordination.

Although French parliamentarians voiced criticism of Qatar’s human rights record when France sent officers to help secure the 2022 Soccer World Cup there, this year’s arrangements with Qatar, Morocco and other nations have prompted less public scrutiny in France.

Hans-Jakob Schindler, senior director of the Counter Extremism Project, said such agreements have been in place during major events in the past, and they are likely to be useful in boosting French police forces’ “capacity with individuals who speak the language of participating teams.”

But coordinating security for this high-risk Olympic Games will remain a challenge, even with international help.

“I really wouldn’t want to be the person responsible for the Olympics in France this year,” Schindler said.