Obama gets second chance to put stamp on court

(CNN) -- President Obama on Friday received his second opportunity to shape the U.S. Supreme Court when Justice John Paul Stevens announced his retirement.

The president named Justice Sonia Sotomayor to the court last year.

In replacing Stevens, Obama likely will nominate a candidate that would maintain the court's ideological balance of five conservative to four liberal-leaning judges.

Government sources said three candidates top an informal list at this early stage. They are Judge Diane Wood of the Illinois-based 7th U.S. Circuit Court of Appeals, Solicitor General Elena Kagan and Judge Merrick Garland of the U.S. Court of Appeals for the D.C. Circuit.

Homeland Security Secretary Janet Napolitano also met privately with Obama last May before Sotomayor's selection and remains in the mix, sources said.

Other possible contenders could be Cass Sunstein, 55, an old law school associate of Obama's and head of a key White House agency, and Massachusetts Gov. Deval Patrick, 53, a longtime friend of the president's. Some insiders reportedly favor Patrick, but he's seeking re-election this fall to governorship.

The White House has quietly but actively prepared for weeks in anticipation of a vacancy, government sources said.

Jeffrey Toobin, CNN's legal analyst, noted Friday that all the justices on the Supreme Court once worked as federal appeals court justices.