New York (CNN) -- Thousands of 9/11 first responders have until midnight Monday to accept a $712 million settlement agreement with the city of New York over illnesses stemming from their exposure to toxic dust at ground zero.
Under the terms of the settlement, 95 percent of some 10,000 plaintiffs, including firefighters, police officers, and emergency workers, must agree to opt in before the settlement can be finalized.
Paul Napoli, a lawyer for the plaintiffs, said that as of Saturday, 92 percent of plaintiffs had agreed to participate.
"I'm very optimistic there will be a deal and it will be done," he said.
In addition to the $712 million from the city, $103 million would be awarded to the plaintiffs from other defendants, including those involved in the massive debris cleanup at the Fresh Kills landfill on New York City's Staten Island following the attacks of September 11, 2001, according to Napoli.
Those who sign onto the settlement would still be eligible for the $7.4 billion James Zadroga 9/11 Health Bill that is making its way through Congress. It seeks to provide free medical coverage for responders and survivors who were exposed to toxins after the attacks.
The House passed the measure on a mostly partisan 268-160 vote in September. The Senate has yet to take up the issue.
In March, U.S. District Court Judge Alvin Hellerstein rejected the city's proposed settlement offer of $625 million, saying that it did not do enough to address the workers' ailments.
Then in June, Hellerstein approved the $712.5 million settlement after listening to testimony from a sampling of some of the 10,000 plaintiffs about the health battles that have plagued them since working at the World Trade Center site.
"I intend to approve this settlement, and I now do so as a fair, adequate and reasonable settlement reflecting hard work and a concern for fairness by all parties," Hellerstein said at the hearing.
Qualifying plaintiffs will be enrolled in a special insurance policy through MetLife that will pay up to $100,000 for certain blood and respiratory cancers diagnosed during the coverage period.
In addition to raising the total compensation, the amended settlement caps attorney fees to 25 percent of the total amount.
Additionally, people claiming severe respiratory issues contracted within seven months of exposure at the World Trade Center site or any surrounding areas could receive $800,000 to $1.05 million. Plaintiffs not suffering from a qualifying injury but who have filed a legal claim fearing they will become sick can receive $3,250. Claims of death proven to be caused by post-9/11 operations could result in $1.5 million in compensation.
"This settlement provides plaintiffs with closure and certainty, while also reserving some funds for future claims," said Christine LaSala, president and CEO of the WTC Captive Insurance Co.
"We believe it is the best path forward for these plaintiffs, as their only other option right now is to proceed to lengthy and costly litigation with an uncertain outcome," she added.
CNN's Cheryl Robinson contributed to this report.