WASHINGTON — President Barack Obama is likely to seek a nominee for the Supreme Court who will not only defend the liberal jurisprudence that reshaped American society in the mid-20th century, but who may also aim to build a progressive legal vision for the century ahead.

Mr. Obama’s ideal candidate, speculates Harvard University professor Laurence Tribe, would “bring majorities together [on the court] around a compelling vision of the law with the elfin touch of someone like [William] Brennan, someone who can move the ocean liner without making terrible waves.” Mr. Tribe taught constitutional law to Mr. Obama and today is among the president’s legal confidants.

The late Justice Brennan, whose 1990 retirement opened a seat for retiring Justice David Souter, molded many of the civil liberties and civil-rights decisions of the 1950s and ’60s, and protected them from a conservative majority in the 1970s and ’80s.

While many of those precedents have survived, if sometimes in diminished scope, liberals have bemoaned more recent conservative successes in framing public debate over the courts and the Constitution.

Few scholars of any ideological stripe dispute the intellectual acumen of Justice Souter, or his fellow liberal justices John Paul Stevens, Ruth Bader Ginsburg and Stephen Breyer. But it is conservative members of the court, such as Clarence Thomas, Antonin Scalia and John Roberts, who have in recent years seized the public imagination, whether through their backgrounds, wit or charisma.

Thus, said Mr. Tribe, the president would want not merely a nominee of academic and professional excellence, but one who — like Mr. Obama himself — can “articulate the vision in a way that speaks to ordinary people.”

The president on Friday said he would seek a nominee “who shares my respect for constitutional values on which this nation was founded and who brings a thoughtful understanding of how to apply them in our time.”

An initial list of candidates, Mr. Tribe said, likely would include federal circuit judges Sonia Sotomayor, Kim Wardlaw and Diane Wood; Stanford law professor Kathleen Sullivan; and Solicitor General Elena Kagan, former dean of Harvard Law School.

During the presidential campaign, Mr. Obama cited the late Chief Justice Earl Warren as exemplifying the type of background he would like to see in a justice. A former California governor, attorney general and district attorney, Mr. Warren had never been a judge. His experience with the criminal-justice system influenced rulings intended to deter once-common forms of police misconduct.

Should Mr. Obama seek a candidate with similar practical experience, he might turn to his Homeland Security secretary, Janet Napolitano, a former U.S. attorney, state attorney general and governor of Arizona. Another candidate with electoral experience is Georgia Chief Justice Leah Ward Sears, who overwhelmingly won her statewide office in a Republican-leaning state.

Douglas Kendall, president of the Constitutional Accountability Center, a liberal advocacy group with ties to some administration officials, said he expects that Mr. Obama “will be looking for a nominee that can thread the needle in the way John Roberts did, pleasing progressives while also appealing to voters in the middle.”

Chief Justice Roberts is an unflinching conservative, but his modest approach and upbeat demeanor helped him win the votes of all Senate Republicans and half the Democrats in his confirmation.

Republicans acknowledge that a Democratic president is likely to nominate a liberal justice, but they warn that they will be on guard against an ideologue.

“I have no illusions about President Obama appointing a conservative,” Sen. Richard Shelby (R., Ala.) said Sunday on CNN’s “State of the Union.” “But if he will appoint a pragmatist, someone who is not an ideologue…I think that would be good for the country.”

Although many Republicans complained when Justice Souter, who was named to the court by Republican President George H.W. Bush, proved more liberal than they had hoped, Sen. Orrin Hatch (R., Utah) said Sunday on ABC’s “This Week” that “it would be a slam dunk if [Mr. Obama] picked somebody who was center-left like Souter. Souter became very liberal, but he also stood for a lot of principles.”