During his career he has faced controversy -- his involvement in a widely-questioned 11th-hour Clinton pardon and the Elian Gonzalez saga, which occurred during his tenure as the department's second-in-command -- but he also has gained a reputation for having a moderate approach to law enforcement issues and a true dedication to public service.
Holder, 57, met Obama at a 2004 dinner party welcoming the junior U.S. senator from Illinois to Washington, where he was headed to Capitol Hill as the nation's only black senator.
Holder recalled the meeting in a cover story in The American Lawyer earlier this year, saying that he and Obama sat next to each other and "just clicked" after discussing their foreign-born fathers, Ivy League educations and zeal for civil service. Additionally, Holder told The American Lawyer, "I think we share a worldview. ... [Obama] is not defined by his race. He's proud of it, cognizant of the pernicious effect that race has had in our history, but not defined by it."
After keeping in touch over the past several years, Obama asked Holder to formally join his campaign last year. When it came time to form a vice presidential candidate search committee last summer, Holder headed up the effort with Caroline Kennedy.
A Career at the Justice Department
Holder's resume is packed with Justice Department experience. Straight out of Columbia Law School in 1976, the New York City native joined the department's newly-formed Public Integrity Section, which prosecutes corruption cases.
In 1988, President Reagan nominated Holder to become an Associate Judge for the Washington, D.C., Superior Court. Five years later, President Clinton tapped him to become the first black U.S. attorney for the District of Columbia, which is the largest U.S. attorney office in the country.
Another first came in 1997, when Clinton again reached out to Holder, asking him to serve as deputy attorney general. Holder became the first African-American to hold the position.
But it was during his tenure as the number two at DOJ that the department, helmed by Attorney General Janet Reno, stirred up considerable controversy. Some incidents could haunt a Holder confirmation hearing, though sources tell ABC News that signs are favorable that Holder would be confirmed.
Additionally, Senate Judiciary Chairman Patrick Leahy, D-Vt., whose committee would have the first opportunity to review Holder's nomination before it goes to a full Senate vote, acknowledged in a statement Tuesday that he has known Holder "for many years" and that he "would make an outstanding nominee, and should have the support of senators from both sides of the aisle if President-elect Obama were to choose him for this critical position."
Controversial Marc Rich Pardon
One of the most divisive acts, the pardoning of fugitive financier Marc Rich, came on the last day of Clinton's second term.
Rich had fled prosecution on charges of tax evasion, racketeering, fraud and making illegal trade deals with Iran, taking up residence in Switzerland.
In the frenzied days before the transition of power to the Bush administration, the department reviewed the pardon request, and Holder graded the application "neutral leaning towards favorable."
Facing accusations that the president granted the pardon because of hefty donations made by Rich's ex-wife Denise -- as well as suspicion that Holder applied the somewhat favorable rating to the pardon application as part of an agreement with Rich lawyer Jack Quinn, who had also served in the Clinton administration as White House counsel, to secure the attorney general spot in a possible Al Gore administration -- Holder testified before the House Oversight and Government Reform Committee in February 2001.
"Knowing everything that I know now, I would not have recommended to the president that he grant the pardon," Holder told the panel. He claimed to have only a "passing familiarity" with the details of Rich's case, and said that he "did not think that the pardon request was likely to be granted, given Mr. Rich's fugitive status."
At the same hearing, federal prosecutors familiar with Rich's case testified that they were not looped in on the process. Additionally, officials claimed that there was a miscommunication between the Justice Department and the White House about the pardon.
House Republicans charged that there was something more sinister afoot. Former Rep. Chris Shays, R-Conn., said at the hearing that everything about the pardon "seems sleazy."
The Elian Gonzalez Saga
In 2000, Reno made the decision to deploy federal agents to the Miami home of Gonzalez, a 6-year-old Cuban boy who had washed ashore in Florida after a tumultuous journey from Cuba that his mother did not survive.
The U.S. government released him to relatives in Miami, but Gonzalez' father, who still lived in Cuba, claimed he should have custody of his son. After a legal battle, the U.S. government determined Gonzalez should be repatriated to Cuba to be with his father.
The photographic image of an agent confronting a scared Gonzalez hiding in a closet with his relatives seared itself in the minds of many Americans.
After the raid, Holder appeared on "Good Morning America." During his interview with Diane Sawyer, he told of comforting his boss, then-Attorney General Janet Reno, while the agents carried out their task.
"At the conclusion of this, I closed the door, at the time of the raid, and I held the attorney general in my arms, and she wept," Holder said.
"She did not want this to happen. She cares a great deal about that community, and hoped and prayed that there was a way in which this thing could have been worked out short of the enforcement action that she very reluctantly had to order."
Life After the Justice Department
Holder left the Justice Department after briefly serving as acting attorney general while Bush nominee John Ashcroft proceeded through his confirmation process. He is currently a partner at the Washington, D.C., law firm Covington & Burling.
While at Covington, he has worked with big league clients, including the NFL, Chiquita Brands International and Merck & Co., Inc.
Holder told The American Lawyer last June that his wife, Washington, D.C., obstetrician Sharon Malone, was not enthusiastic about his potential return to government work.
"[She] tells me that I won't be going anywhere except back to my law firm," he said. "So I think President Obama is going to have to talk to Sharon, and she's a pretty formidable person."
Though it doesn't come with the more-than-comfortable salary of a law firm partner, the draw to public service could lure Holder back to the Justice Department.
"What's great about the Obama presidency is that so many people, like Eric Holder, are willing to forgo big incomes and endure intrusive vetting to get back into public service," said Doug Kendall, president of the Constitutional Accountability Center. "What he's doing at a loss to his pocketbook and family life is what America needs to right the ship."
Holder has made it clear that he agrees with those who believe the country is on the wrong path.
Last summer, Holder repudiated the Bush administration during a speech at the American Constitution Society's national convention.
Referring to the "disastrous course" traveled by the Bush administration, Holder called for the closure of the Guantanamo Bay detention facility, a condemnation of torture and the end to warrantless domestic surveillance.
"Our needlessly abusive and unlawful practices in the 'War on Terror' have diminished our standing in the world community and made us less, rather than more, safe," Holder said.
"For the sake of our safety and security, and because it is the right thing to do, the next president must move immediately to reclaim America's standing in the world as a nation that cherishes and protects individual freedom and basic human rights."
If he ascends to the attorney general post, Holder could significantly impact the policies he -- and President-elect Obama -- have so vocally renounced.
ABC News' Jake Tapper and Ariane de Vogue contributed to this report.