Legislators and pundits have been baying for the blood of James Clapper, the Director of National Intelligence, over last week’s revelations of wide-ranging NSA surveillance. But the next person on their hit-list could be someone even Washington doesn’t know too well. Meet Rajesh [Raj] De, the general counsel for the US National Security Agency, and the lawyer with perhaps the biggest influence on the Obama administration’s approach to large-scale surveillance.

De is a publicity-shy policy wonk. What makes him so influential is that as well as having been a lawyer in private practice, he has worked for the Senate Homeland Security Committee, held a senior policy job at the Justice Department, and—before leaving for the NSA a year ago—was deputy staff secretary and then staff secretary at the White House, the latter a coveted position in which De reviewed “every single piece of paper before it goes to President Obama.”

And, as this lengthy Feb. 27 speech indicates, De is insistent that the NSA is doing nothing wrong. In the speech—worth reading in full as a window into the intelligence establishment’s mindset and view of itself—he contends that the NSA is overly diligent when it comes to legally and properly conducting surveillance in the United States and around the world. His job is all the harder because NSA is also being buffeted, he says, by enormous and rapidly changing threats on the one hand—and legal and technical challenges on the other, thanks to the explosive growth in many forms of communications technology.

That makes him an obvious target for those attacking the administration on its civil-liberties record. De will now spend much of his time dealing with demands from Congress, scrutiny by the media and lawsuits from the American Civil Liberties Union and others. And Obama’s opponents may well try to use De’s closeness to him to ensnare the president in the surveillance controversy.

However, De also has plenty of supporters. Friends and former colleagues say he has reached such stratospheric professional heights not just because of a brilliance in understanding national security policy and law, but because he’s just so… nice. “He’s got a spine of steel, but there’s a real sweetness to him,” one former colleague on the 9/11 Commission told Quartz. De was one of the commission’s youngest members, fresh from Harvard and Harvard Law, but developed a reputation for pushing the national security Mandarins to actually cooperate with investigators, that former colleague and others said.

“Raj De is a brilliant, level-headed, and not flashy guy. He’s been a great public servant,’’ says Neal Katyal, Obama’s former acting solicitor general, who worked with De at the Justice Department.

For his part, De can easily defend his time at NSA by saying the controversial programs were in place long before he took over, friends and colleagues told Quartz. Besides, they say, De has been pushing for more transparency and openness about NSA’s activities, long before NSA contractor Edward Snowden started leaking classified documents to The Guardian and The Washington Post.

“This is a guy of great, great intellectual heft and policy seriousness,” said De’s former 9/11 colleague, who says he can’t talk for the record because he is now a high-ranking Obama national security official. “The irony here is that this is someone with tremendous integrity, who really thinks and cares about security and secrecy policy-making, while caring very passionately about civil liberties.”