Nobody but President Obama and perhaps his closest advisers know who he will nominate to replace Justice Antonin Scalia after his unexpected death Saturday. And it seems likely that Republicans will do all they can to prevent a nomination process before 2017.  But Jeffrey Toobin, CNN legal analyst and New Yorker writer, speculated on Twitter it would be Sri Srinivasan, a former senior Justice Department official who Obama fought to confirm for a seat on the U.S. Court of Appeals in the District of Columbia.

Toobin wrote about Srinivasan in a short 2013 piece in the New Yorker, headlined, "The Supreme Court nominee in the waiting."

The D.C. Circuit has long operated as a Supreme Court farm team (John Roberts, Antonin Scalia, Clarence Thomas, and Ruth Bader Ginsburg played their AAA ball there), and Republicans have worked with zeal, and amazing success, to keep Obama from placing a single judge on that court. ...
Srinivasan, who is forty-six years old, is currently the Obama Administration’s principal deputy solicitor general. He’s had twenty or so arguments in the Supreme Court, including part of the Administration’s attack on the Defense of Marriage Act last month....
He has the sort of impeccable credentials that are much beloved by the Supreme Court bar, though Srinivasan’s own views on the Constitution are more difficult to discern. He has written many briefs but few articles that reveal his own thinking. He is a protégé of Walter Dellinger, the acting Solicitor General in the Clinton Administration and a (mostly) beloved (mostly) liberal figure in the world of the Supreme Court. The safe assumption seems to be that Srinivasan would be the same kind of moderate liberal as Sonia Sotomayor and Elena Kagan (and Ruth Bader Ginsburg and Stephen Breyer, for that matter).

Srinivasan's nomination to the District Court of Appeals was previously part of an effort to tilt it away from its conservative leanings, one reason that Republicans had fought his nomination. But Srinivasan recently said the court has not tilted in any significant way, despite him and several other left-leaning colleagues joining the court under Obama.

“If we lived in a world where we had the rule of a judge, rather than the rule of law, you would have seen an absolute sea change, an avulsive change in the law as it was interpreted, applied and rendered by our court,” Srinivasan said, according to Politico. “And I think in at least some spheres there was probably some apprehension about that — or glee about that — depending on one’s perspective [but] we didn’t see an immediate sea change in decisions, we didn’t see an overruling of prior precedent, we didn’t see an immediate call to take en banc any case in which judges make a decision that other judges on the court might disagree with."