NPR has learned that Supreme Court Justice David Souter is planning to retire at the end of the court's current term.
The court has completed hearing oral arguments for the year and will be issuing rulings and opinions until the end of June.
Souter is expected to remain on the bench until a successor has been chosen and confirmed, which may or may not be accomplished before the court reconvenes in October.
At 69, Souter is nowhere near the oldest member of the court, but he has made clear to friends for some time now that he wanted to leave Washington, a city he has never liked, and return to his native New Hampshire.
Now, according to reliable sources, he has decided to take the plunge and has informed the White House of his decision.
Souter's retirement would give President Obama his first appointment to the high court, and most observers expect that he will appoint a woman.
The court currently has one female justice — Ruth Bader Ginsburg, who is recovering from cancer surgery.
Obama was elected with strong support from women.
An Obama pick would be unlikely to change the ideological makeup of the court. Souter, though appointed by the first President Bush, generally votes with the more liberal members of the court, a group of four that is in a rather consistent minority.