WASHINGTON (AP) — Justice David Souter is planning to retire after more than 19 years on the Supreme Court, giving President Barack Obama his first chance to fill a vacancy on the high court.

The White House has been told that Souter will retire in June, when the court finishes its work for the summer, a source familiar with his plans said Thursday night. He almost certainly would remain on the bench until a successor is confirmed.

The source spoke to The Associated Press on condition of anonymity because he was not authorized to speak for Souter.

Souter had no comment Thursday night, a Supreme Court spokeswoman said.

Souter’s retirement is unlikely to alter the ideological balance on the closely divided court because Obama is certain to replace the liberal-leaning justice with someone with similar views.

But the vacancy could lead to another woman on the bench to join Justice Ruth Bader Ginsburg, currently the court’s only woman.

At 69, Souter is much younger than either Ginsburg, 76, or Justice John Paul Stevens, 89. Yet those justices have given no indication they intend to retire soon and Ginsburg said she plans to serve into her 80s despite her recent surgery for pancreatic cancer.

Interest groups immediately began gearing up for what could be a grueling battle over the president’s first pick to the high court.

“We’re looking for President Obama to choose an eminently qualified candidate who is committed to the core constitutional values, who is committed to justice for all and not just a few,” said Nan Aron, president of the liberal Alliance for Justice.

Some of the names that have been circulating include recently confirmed Solicitor General Elena Kagan; U.S. Appeals Court Judges Sonya Sotomayor, Kim McLane Wardlaw, Sandra Lea Lynch and Diane Pamela Wood; and Leah Ward Sears, chief justice of the Georgia Supreme Court. Men who have been mentioned as potential nominees include Massachusetts Gov. Deval Patrick, Harvard Law professor Cass Sunstein and U.S. District Judge Ruben Castillo of Chicago.

Souter has never made any secret of his dislike for Washington, once telling acquaintances he had “the world’s best job in the world’s worst city.” When the court finishes its work for the summer, he quickly departs for his beloved New Hampshire.

He has been on the court since 1990, when he was an obscure federal appeals court judge until President George H.W. Bush tapped him for the Supreme Court.

Bush White House aide John Sununu, the former conservative governor of New Hampshire, hailed his choice as a “home run.” And early in his time in Washington, Souter was called a moderate conservative.

But he soon joined in a ruling reaffirming woman’s right to an abortion, a decision from 1992 that remains still perhaps his most noted work on the court.

Souter became a reliable liberal vote on the court and was one of the four dissenters in the 2000 decision in Bush v. Gore that sealed the presidential election for George W. Bush.

Yet as Souter biographer Tinsley Yarbrough noted, “he doesn’t take extreme positions.” Indeed, in June, Souter sided with Exxon Mobil Corp. and broke with his liberal colleagues in slashing the punitive damages the company owed Alaskan victims of the Exxon Valdez oil spill.

Souter is the court’s 105th justice, only its sixth bachelor. He works seven days a week through most of the court’s October-to-July terms, a pace that he says leaves time for little else. He told an audience this year that he undergoes “an annual intellectual lobotomy” each fall.

Souter earned his bachelor’s and law degrees from Harvard sandwiched around a stay at Oxford University as a Rhodes scholar.

He became New Hampshire’s attorney general in 1976 and became a state court judge two years later. By 1990, he was on the federal appeals court in Boston for only a few months when Bush picked him to replace Justice William Brennan on the Supreme Court.

National Public Radio first reported Souter’s plans Thursday night.