President Obama is expected to nominate Merrick Garland to serve on the Supreme Court. Here is what you need to know about Garland. (Claritza Jimenez,Gillian Brockell/The Washington Post)

To some, Merrick Garland’s experience and demeanor could make him the quintessential Supreme Court candidate for a Democratic president.

A magna cum laude Harvard Law School graduate, he clerked not just for any Supreme Court justice but for William J. Brennan Jr., the legendary liberal champion. He was a partner at a prominent Washington law firm, then ascended the ranks at the Justice Department, where he oversaw two of the biggest domestic terrorism cases in U.S. history.

Now, the well-regarded chief judge of the D.C. federal appeals court is under serious consideration to be President Obama’s nominee for the nation’s highest court, according to people familiar with the deliberations. “Merrick is in his own league . . . He’s pretty unassailable from a reputational standpoint,” said a person close to the selection process who spoke on the condition of anonymity to discuss private conversations.

But Garland could face a number of political factors that would put him out of contention, according to legal experts and others who have spoken with administration officials. Garland’s two-decade track record as a judge may wind up working against him, these people said, because if Republicans pore over his career, they may find more to use against him in a fierce confirmation battle. By contrast, many of the others being considered by the White House are younger and have had shorter careers.

In addition, Garland is a white male at a moment when Democrats may want a nominee around whom they can rally minorities in the party’s base, particularly during a presidential election year. Civil rights groups, for example, are pressing the nation’s first African American president to nominate the first black woman to the court.

Barbara R. Arnwine, president of the Transformative Justice Coalition and a longtime civil rights activist, said that while Garland brings “incredible qualifications and an impressive background and résumé,” she believes a number of female black judges are just as qualified. Nominating Garland, she said, “would send a message that the status quo of American privilege is still in place.”

Given that Republicans in the Senate have vowed to block any nominee, the president’s pick could be more important for its political symbolism.

“You know the person isn’t getting confirmed,” said one legal expert who closely follows the Supreme Court and spoke on the condition of anonymity out of respect for Garland, whose nomination he considers unlikely. “Why would you disappoint every significant constituency when you’re trying to motivate people?”

Garland was also a finalist for the first two Supreme Court vacancies Obama filled, according to sources who were close to those processes. But even if he is not chosen this time, people who know him say he feels honored just to be considered.

“He is very content to be the chief judge of the D.C. Circuit. It’s a wonderful job, and he’s wonderfully suited to it,” said Jamie Gorelick, a former deputy attorney general who worked with Garland at the Justice Department in the Clinton administration and considers her former colleague “supremely qualified” for the high court. “Getting an appointment to the Supreme Court requires lightning to strike.”

Gorelick praised Garland’s role at the Justice Department in supervising the massive investigations that led to the prosecutions of the bombers of the federal building in Oklahoma City and the Unabomber.

“We had a lot of very seasoned prosecutors, but when you have a matter that is both substantively difficult and cuts across the department, a really talented person such as Merrick will lead those,” said Gorelick, who added that Garland is a “brilliant lawyer and judge” who is known to be highly collegial even with colleagues across the ideological spectrum.

Garland was nominated to the U.S. Court of Appeals for the District of Columbia Circuit by President Bill Clinton in 1997 and confirmed on a 76-to-32 vote. He won support from 32 Republicans.

In 2010, when Garland was under consideration for the Supreme Court vacancy that went to Justice Sonia Sotomayor, Sen. Orrin G. Hatch (R-Utah) told Reuters that he had known Garland for years and that he would be “a consensus nominee.”

Hatch, a powerful voice on judicial selection, said then that there was “no question” Garland could be confirmed.

Garland is among at least six candidates known to be under consideration. The others are judges Sri Srinivasan and Patricia A. Millett, more recent appointees to the D.C. appeals court that Garland heads; Jane L. Kelly, an appeals court judge based in Iowa; Paul J. Watford, an appeals court judge in California; and Ketanji Brown Jackson, a U.S. district judge in Washington. At 63, Garland is by far the oldest candidate for the lifetime Supreme Court appointment.

“He’s extremely well qualified, and he’s a superb judge,” said Michael Greenberger, a University of Maryland law professor who was a senior Justice Department official in the Clinton administration. “He’s widely revered on both sides of the aisle. If the White House is looking to get somebody through . . . he would be a great candidate.”