NPR and MSNBC both reported Souter’s retirement, with NPR saying he would retire at the end of the current term, but only after a successor had been chosen and confirmed. That could take until October.
White House officials did not immediately respond to questions about the retirement of Souter, 69, which became the subject of intense interest Thursday when the Associated Press reported that Souter, unlike other justices, had not hired law clerks for the coming session.
Souter hails from the court's relatively liberal branch, so his retirement is unlikely to represent a deep shift in the balance of power among the Supremes, but rather a deepening and renewal of the left end of the bench.
But Obama will face competing imperatives, including the pressure to appoint the first Hispanic to the Supreme Court and his own ties to prominent legal academics beginning with his years at Harvard Law School.
During his campaign for the White House, Obama suggested he'd take personal considerations into account in selecting judges.
"We need somebody who's got the heart, the empathy, to recognize what it's like to be a young teenage mom. The empathy to understand what it's like to be poor, or African-American, or gay, or disabled, or old. And that's the criteria by which I'm going to be selecting my judges," he told a Planned Parenthood conference in 2007.
The top candidate, on paper, is Judge Sonia Sotomayor, a Clinton appointee to the Second Circuit Court of Appeals. She meets the empathy criteria, having grown up poor in the South Bronx, as well as Obama's preference for sterling credentials, having graduated from Yale Law School.
Solicitor General Elana Kagan, a former dean of Harvard Law School, has also been mentioned as a likely pick.