Graham also defended the administration's drone program, saying it "has been very effective."
"We've killed 4,700," Graham added. "Sometimes you hit innocent people, and I hate that, but we're at war, and we've taken out some very senior members of Al-Qaeda."
The comments come as a number of top legislators and U.S. officials are debating whether the Obama administration needs to change how it conducts drone strikes. Earlier in February, NBC News reported on a Department of Justice (DOJ) memo laying out the Obama administration's legal rationale for conducting lethal drone attacks on U.S. citizens abroad.
The memo argues that the U.S. can conduct a drone strike if the target has been deemed an "imminent threat" by a U.S intelligence official, it's impossible to capture the target and the strike falls in line with international wartime laws pertaining to the use of force.
But the leaked memo only sparked more congressional questions, with lawmakers pressing top White House counterterrorism adviser John Brennan, President Obama's pick for CIA director, on the administration's program. Lawmakers have called for more details on the strikes and want the DOJ to release its actual legal briefs defending the practice of targeting U.S. citizens abroad.
Former Secretary of Defense Robert Gates recently argued that while the Obama administration has not abused its use of drones, there should be additional oversight.
"And so I think — I think this idea of being able to execute, in effect, an American citizen, no matter how awful, having some third party being ... having a say in it or perhaps some — informing the Congress or the intelligence committees or something like that ... I think some check on the ability of the president to do this has merit, as we look to the longer term future," Gates said.
Democratic Sens. Dianne FeinsteinDianne FeinsteinDems get it wrong: 'Originalism' is mainstream, even for liberal judges Human rights leaders warn against confirming Gorsuch Feinstein sees slipping support among California voters: poll MORE (Calif.) and Patrick LeahyPatrick LeahyDems get it wrong: 'Originalism' is mainstream, even for liberal judges Live coverage: Day three of Supreme Court nominee hearing Dems land few punches on Gorsuch MORE (Vt.) have both expressed interested in the idea and said they were open to hearings examining the matter.