As Justice John Paul Stevens strongly hinted in interviews this week that he would step down soon after more than 34 years on the high court, the question is more than merely rhetorical. Stevens turns 90 on April 20. While he could go for the record as the nation's longest-serving Supreme Court justice, he has hired only one clerk for next term instead of the usual four, a telltale sign he is considering hanging up his black robe for good.
The one-time moderate Republican was appointed to the court by President Gerald Ford in 1975. Over the years, he has morphed into the leader of the court's liberal wing, now in the minority. His departure could set off a hot summertime confirmation confrontation on Capitol Hill. Pennsylvania Democratic Sen. Arlen Specter, former Republican chairman of the Senate Judiciary Committee, predicted a filibuster fueled by partisan gridlock if Stevens exits before the sure-to-be-contentious midterm elections in November.
Legal experts say it is too soon to know who will emerge on the high court's left until President Barack Obama announces his choice. Like his first pick last year, Sonia Sotomayor, whoever replaces Stevens is unlikely to tip the ideological balance on the bench. Under Chief Justice John Roberts, the court has been moving right, especially when Justice Anthony Kennedy swings his vote that way.
Given Democrats' lack of a filibuster-proof majority in the Senate, which must confirm the president's selection, and the sometimes-contentious hearings to confirm Sotomayor, it's doubtful Obama will pick someone as liberal as Stevens. His finalists to replace David Souter were hardly liberal mirror images of conservative maverick Justice Antonin Scalia.
Barry Friedman, a constitutional law professor at New York University, said it is important that Obama choose someone "with leadership capacity" but rejects the idea that the left needs its own Scalia to vocally champion its views on the court.
"I think that's wrong," he told AOL News. "Scalia has been an ineffective justice. It takes five votes to get anything done and he often insists on writing for himself. Same with [fellow conservative] Clarence Thomas. The president needs someone who can build coalitions. Stevens was pretty good at that."
Pamela Harris, a former law clerk for Stevens, said none of the current liberal justices has demonstrated the ability to weave majorities in close cases.
"I don't think there is anybody who can replace Justice Stevens in the role that he's been playing as a leader of the more liberal coalition on the court," said Harris, now executive director of Georgetown University's Supreme Court Institute. "I do not think there is anybody sitting on the court today who can fill that gap."
Harris said Stevens "exercised real leadership" in cases where Kennedy's vote was crucial. She noted Hamdan v. Rumsfeld, in which the court struck down President George W. Bush's military commissions system as unconstitutional. "Victories like that may be harder to win," she said.
Still, there are contenders:
Ruth Bader Ginsburg: By virtue of her seniority and philosophical inclination, the leadership mantle should be hers for the inheriting. But Ginsburg, who turned 77 last month, has suffered from poor health, most recently undergoing surgery for what doctors diagnosed as early-stage pancreatic cancer. Despite the disease's bleak survival rates, Ginsburg has shown no signs of stepping down and recently fired back at a Republican senator who suggested she isn't long for the bench.
As the court turned right under Roberts, and with the help of fellow Bush appointee Samuel Alito, Ginsburg has spoken out more. When a sharply divided court ruled against tire factory supervisor Lilly Ledbetter in a pay discrimination lawsuit, the former women's rights advocate read a rare but stinging dissent from the bench.
"By dint of longevity, power of intellect and integrity, Stevens was a very powerful influence," said Harvard University law professor Richard Fallon. "I don't have the sense that [Ginsburg] is boldly visionary."
"Justice Ginsburg is sadly too frail, even as her strength of conviction is unquestioned," said Douglas Kmiec, a conservative Pepperdine University law professor now serving as U.S. ambassador to Malta. He gave his views in an e-mail to AOL News, noting his views "are mine personally and do not represent the U.S. Department of State or the president necessarily."
Stephen Breyer: Though he is junior to Ginsburg by a year -- both were selected by President Bill Clinton -- Breyer may be the leading progressive voice on the court, a prolific writer who can go word-for-word with Scalia.
"If there is a leader, it is Breyer," said University of Texas at Austin law professor Sanford Levinson. "He's written books, he goes out and makes talks in ways [Ginsburg] doesn't, he debates Scalia. By all accounts, he is very, very upset about the current trend of the court and has an incentive to try to lead it."
Kmiec disagrees. Breyer's "penchant for the complex makes it unlikely that he can articulate court rationales that will attract his colleagues to a truly progressive vision," he wrote.
Sonia Sotomayor: If she spends a year or less as the junior member, Sotomayor could find herself elevated to a more high-profile role, Harris said. Even as the newest justice, the Bronx native has shown nary a hint of freshman jitters, bluntly throwing out questions in frequent and rapid order from the bench.
"Sotomayor is a definite possibility," Kmiec wrote. "She has the respect of the entire court for her attention to record detail; for her hard work; and for her unwillingness to be cowed by the strongest conservative voice (Scalia) or strategist (Roberts). Her progressive vision is also reasonably clear, looking out for the underserved minority especially."
But, he added, Sotomayor may be less able to persuade Kennedy. "They frankly speak in entirely different judicial idiom," he wrote.
None of the above: As the media speculates about whom Obama will pick if Stevens steps down, the real next leading liberal may be among them.
"The progressive leader will be -- as they say in baseball -- a player to be named later," Kmiec said.