Senate Republicans on Tuesday said Congress must revisit how U.S. national security agencies select civilian contractors.
The comments come a day after 12 people were killed by a lone gunman at Washington's Navy Yard. Aaron Alexis, a contractor who also died at the scene, has been identified as the shooter by police.
"It may be time for a [congressional] review to see how well these contractors are doing their jobs" in terms of vetting candidates for sensitive, national security positions, Sessions told reporters on Capitol Hill.
Sen. Lindsey Graham (R-S.C.) openly questioned whether the process government agencies use to vet civilians before allowing them access to highly-sensitive national security issues is "fundamentally broken."
"What are we doing to check who works for the government in a civilian capacity?" said Graham, who is a senior member of the Senate Armed Services Committee. "Is it because we do not have the resources or is the system just fundamentally broken."
Alexis was identified as a former Navy petty officer 3rd class who enlisted in the Navy in 2007 and was reportedly working as an information technology contractor at the Navy Yard.
While in the Navy, Alexis was reportedly arrested on misdemeanor weapons charges in Ft. Worth, Texas, which led to him leaving the service in 2011.
Alexis's hiring as a Navy IT contractor, despite his criminal record, remains the biggest question mark for Graham and other lawmakers.
"Of all the things I have heard about the Navy Yard [shootings], that question looms the largest for me," he said.
When asked if contractor standards have become too lax, Graham replied "I am going to go out on a limb and say yes."
Lawmakers also raised concerns about contractors after former National Security Agency contractor Edward Snowden leaked reams of classified information on the agency's domestic intelligence programs to the media.
"I think it is a serious question [since] we have seen this [happen] in a lot of different areas" within government agencies, Sessions said.
Security and background checks on contractors are continually being "farmed out" to the private sector, which has led to serious gaps in the vetting process, he added.
In June, Sen. Dianne Feinstein (D-Calif.) said Congress would consider changes to the rules for contractors in the wake of the Snowden leaks.
Calls for such legislation are again gaining traction in the Senate after Monday's mass shootings.
Sen. Jim Inhofe (Okla.), the top Republican on the Senate defense panel, said Monday that massive cuts to the defense budget are clearly connected to the failures in the Pentagon's contractor hiring process.
"To me, that is the most important [issue]," he said, adding those problems may have helped contribute to the chain of events that led to Monday's deadly shootings.