The Maryland Democrat is taking the lead on the issue, since the National Security Agency's (NSA) headquarters are located at Ft. Meade, Md., Senate Majority Whip Dick DurbinDick Durbin McConnell: I’m very sympathetic to 'Dreamers' Senate Dems move to nix Trump's deportation order Dem senators call for independent Flynn probe MORE (D-Ill.) told reporters on Tuesday.
"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."
Mikulski's office has yet to formally request hearings on the matter, spokeswoman Rachel MacKnight told The Hill on Tuesday.
However, Snowden's classified leaks of NSA programs had left the Fort Meade community "reeling," according to Mikulski.
"Maryland is reeling from this one, national security agencies in our state ... and people are asking, why does a kid who couldn't make it through a community college make $200,000 grand a year and be exposed to some of our most significant secrets?" she said during Tuesday's Senate Appropriations defense subcommittee hearing.
"So [the Senate will] have a lot of hearings on this," she told Defense Secretary Chuck HagelChuck HagelWho will temper Trump after he takes office? Hagel: I’m ‘encouraged’ by Trump’s Russia outreach Want to 'drain the swamp'? Implement regular order MORE and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey, who were testifying on the Pentagon's fiscal 2014 budget bill before the Senate panel.
Snowden, who has said he was a former undercover CIA analyst, had been working for three months as a contractor with Booz Allen Hamilton when he leaked details of the programs to The Guardian and The Washington Post.
In an interview with The Guardian, he said he knew of the programs for years and was disappointed that President Obama had not stopped them.
The case sparked questions about how a 29-year-old with a GED who left the Army Reserves after less than five months could have had access to such sensitive material.
It has also created concerns on Capitol Hill over how private contractors with the intelligence community are vetted, and how much insight are they allowed into highly-classified intelligence programs.
One program was designed to collect cellphone data from Verizon customers to track terror threats and a second program, PRISM, collected data from tech companies on foreign Internet users.
On Monday, Senate intelligence committee chief Dianne FeinsteinDianne FeinsteinDem: Trump's China trademark looks like a quid pro quo Senate advances Trump's Commerce pick Flynn told FBI he didn't talk sanctions with Russian envoy: report MORE (D-Calif.) said Snowden's actions were tantamount to treason.
Snowden's backers claim his actions shed much needed light on efforts by the U.S. intelligence community to conduct surveillance on American citizens.
For his part, Durbin said he sided with Feinstein's take on Snowden.
"I do not put him in the class of Daniel Ellsburg," Durbin said, referring to the Pentagon analyst who leaked the infamous Pentagon Papers, which disclosed details of America's failing war effort in Vietnam.
"I do not think this quite fits into that same category," Durbin said.
Snowden "took an oath not to disclose information and he turned around and did it," Durbin said.
"If that became commonplace, it would be next to impossible to keep America safe," he added.