It could be seen as the sincerest form of flattery: Ask some activists on the left the kind of Supreme Court justice they would like to see a President Obamaappoint, and the name you hear most is the same justice they most often denounce.

They want their own Antonin Scalia. Or rather, an anti-Scalia, an individual who can easily articulate a liberal interpretation of the Constitution, offer a quick sound bite and be prepared to mix it up with conservative activists beyond the marble and red velvet of the Supreme Court.

Some have even mentioned Sen. Hillary Rodham Clinton for the role, although there is no evidence it would interest her or that Obama would consider his former rival for the Democratic presidential nomination for the court. But as the Supreme Court takes its traditional spot in the background of the presidential campaign, there is a longing on the left for a justice who would energize not only the court’s liberal wing, but also the debate over interpreting the Constitution.

“Someone with vision,” said Doug Kendall, who recently helped found a new liberal think tank called the Constitutional Accountability Center. “Someone who looks hard at the text and history of the Constitution, as Justice Scalia does, and articulates a very clear idea of how that text points to liberal and progressive outcomes.”

Liberal legal activists have consistently lagged behind conservatives in convincing their partisans that the court should be a voting issue. The court remains ideologically split, but any openings presented to the next president are almost sure to come from within the court’s liberal wing. The two oldest members of the court are Justices John Paul Stevens, 88, and Ruth Bader Ginsburg, 75.

If John McCain were elected, the appointment of a conservative justice could immediately reshape the court. The senator from Arizona might be forced to temper his choice to accommodate confirmation by a solidly Democratic Senate, but his nominee would undoubtedly be far to the right of either Stevens or Ginsburg, potentially solidifying a five-member conservative majority. President Bush‘s appointments to court, Chief Justice John G. Roberts Jr. and Justice Samuel A. Alito Jr., are both relatively young and are expected to be fixtures for decades.

If Obama had the opportunity to make an appointment, it would be only the fourth nomination from a Democratic president in more than 40 years. And for activists on the left, it could signal the opportunity to create a new dynamic for the court.

“It is a court with no true liberal on it, the most conservative court in 75 years,” said Geoffrey Stone, a law professor at the University of Chicago, where Obama once taught constitutional law. “What we call liberals on this court are moderates, or moderate liberals, if you want to get refined about it.”

Stone notes, as he said Stevens has, that every justice on the current court with the exception of Ginsburg is more conservative than the justice he replaced — a natural evolution given that seven of the nine were appointed by Republican presidents.

Harvard law professor Lani Guinier hopes to get scholars, as well as judges, to rethink the role of a Supreme Court justice, a role she describes as “the justice as a teacher in a national seminar, an educator.”

“They’re not just making laws and delivering those tablets from Mount Olympus,” Guinier said. “The project of being a Supreme Court justice is also a project of being an important citizen in a democracy.”

While Guinier said she would not necessarily argue that the next president should nominate a politician, she said it was important to “make the court more democratically accountable.”

“I think Hillary Clinton would bring to the court a range of experiences that the court doesn’t presently have access to,” Guinier said, noting that Clinton has run for two political offices and traveled all over the country engaging ordinary people in conversations “about real challenges that affect their lives.”

James Andrew Miller, an assistant to former Senate majority leader Howard H. Baker Jr., wrote an op-ed in The Washington Post in May suggesting Clinton for the court, and said he was “just blown away” by the response.

Massachusetts Gov. Deval Patrick (D), a former Justice Department official and prominent Obama friend, has also been mentioned as a potential court appointee, and such a move would not be unprecedented. There is a substantial list of justices who once held political office. Most famously, President Dwight D. Eisenhower made good on his promise of an appointment to his onetime rival, California governor Earl Warren.

But the jobs could hardly be more different — the somewhat solitary pursuits of a justice versus the glad-handing and collaborative responsibilities of a politician. But someone who has been tested by campaigns for public office might be more comfortable in the public arena, argued Dawn Johnsen, a former Clinton administration official who now teaches law at Indiana University, who said there “is a desire to have justices talking to the American people beyond their opinions.”

Cass R. Sunstein, an informal Obama adviser now at Harvard Law School, last year instigated the debate by lamenting the “absence of anything like a heroic vision on the court’s left” to counteract Scalia and Justice Clarence Thomas.

John Podesta, once President Bill Clinton‘s chief of staff and now president of theCenter for American Progress, recently told the liberal American Constitution Society that the idea of “balancing” the courts with judges on the extreme left was not a good idea.

“We don’t need to play that same game,” he said — a notion not particularly well-received by those in the audience.

Christopher L. Eisgruber, provost at Princeton University and author of a book about Supreme Court nominations titled “The Next Justice,” said liberal activists seemed split between “breaking the mold a little between liberals and conservatives” and putting “somebody in the opposite corner in the boxing ring with Antonin Scalia.”

Obama himself has been opaque and even contradictory about his criteria for a justice. He voted against both Roberts and Alito, and has said he sees Ginsburg and Justices Stephen G. Breyer and David H. Souter as the kinds of “sensible” justices he would favor.

Yet, as the court’s term ended last month, he praised the court’s decision in support of an individual right to gun ownership that struck down the District of Columbia’s handgun ban, a decision in which Roberts and Alito were in the majority and liberals dissented.

Likewise, he disagreed with the court’s decision that the death penalty may not be applied to child rapists, where Ginsburg, Breyer and Souter were in the majority and the conservative justices were in dissent.

Obama has said that justices will be in agreement 95 percent of the time, and in the other cases he looks for a judge “to bring in his or her own perspectives, his ethics, his or her moral bearings.”

Republican critics have mocked that description for not including the word “Constitution” and contrasted it with McCain’s vow to appoint judges “who have a proven record of strict interpretation of the Constitution of the United States.”

Kendall winced at Obama’s words. He said they make it sound as if one must look outside the law and the Constitution to get the results political progressives are looking for while they are provided for in guarantees of equal protection and due process. McCain’s description will always be more palatable to the public, Kendall said.

Research editor Alice Crites and staff researcher Madonna Lebling contributed to this report.