"These men and women have access to some of our most sensitive national security information," Nelson said in a letter to Senate Intelligence Committee Chairwoman Dianne Feinstein (D-Calif.) on Thursday.
Further, the Florida Democrat is demanding a congressional investigation into how private contractors vet and grant top-secret or higher levels of clearance to their employees.
"Multiple incidents such as this warrant an Intelligence Committee investigation to determine more broadly how private contractors are managing the hiring and monitoring of employees who have top-secret clearance from the government and who handle highly classified information," according to Nelson.
Snowden, who also was a contractor with Booz Allen while at the NSA, leaked classified details of two previously unknown domestic intelligence programs to the media earlier this month.
One program, code-named PRISM, was designed to pull data from tech companies on foreign Internet users. The second program allowed the NSA to sweep all cellphones on the Verizon network.
After the disclosures, Feinstein told reporters she would push for legislation to limit the access that federal contractors have to highly classified information.
"We will consider changes," Feinstein told reporters after a classified briefing with administration officials on the NSA leaks last Thursday.
"We will certainly have legislation which will limit [or] prevent contractors from handling highly classified data," she said.
Sen. Saxby Chambliss (R-Ga.), the ranking member on the Senate intel committee, said after the same briefing that it’s clear the U.S. needs to "do a better job of making sure that our top-secret clearances go to only those individuals that deserve it."
"I think there are some changes that we’re going to look at, but I don’t know that it needs to be done legislatively," Chambliss said. "We just have to wait and see."
Last Wednesday, Senate Majority Whip Dick Durbin (D-Ill.) said there were still serious questions on how Snowden "ended up with access to some of the most sensitive data in American security."
"Who in the world made that decision?" he added. "I want to know more about [Snowden], but what I have learned so far is troubling."
News of the Bennett incident has only turned up the heat on the private contracting corps that began when news of the Snowden leaks went public.
In 2008, Bennett was brought on as counter-threat finance analyst in Central Command’s Joint Intelligence Operation Center at MacDill Air Force Base, Fla.
As a contractor analyst, Bennett's job was to track financial transactions and determine various funding streams used by al Qaeda and other militant extremists groups.
As part of the job, Bennett was granted top-secret/secure sensitive compartmentalized information (SCI) clearance by Booz Allen.
Top Secret/SCI clearance grants an individual access to some of the most sensitive and highly classified intelligence kept by the military and intelligence agencies.
But a 2011 Tampa Tribune article uncovered that Bennett was convicted on misdemeanor charges of lying to government officials while trying to secure a visa for a South African national.
Despite his conviction, Bennett was able to pass the security clearance vetting process and received Top Secret/SCI clearance in 2008.