Toomey made his case and claimed an unlikely victory after his aides dug deep into Adegbile's role overseeing lawyers at the NAACP Legal Defense Fund. Decades after Abu-Jamal's 1982 conviction and years after his death sentence had first been thrown out, the fund represented him in the fight over his resentencing.
Toomey's staff compiled records that the senator used to support his argument that Adegbile went beyond legal work and joined in the international campaign to portray Abu-Jamal as an innocent man and a victim of racism.
Enraged Democrats accused Republicans of wild exaggerations, but the shadow of that international campaign helped sway two area Democrats, Sens. Bob Casey (D., Pa.) and Chris Coons (D., Del.), to cast critical votes against the nominee even as they praised his qualifications.
Five more Democrats, largely from conservative states, also opposed Adegbile, handing Obama an embarrassing defeat. (An eighth, Senate Majority Leader Harry Reid, voted "no" for procedural reasons.)
Toomey did not meet with Adegbile. But his staff scoured legal briefs, court opinions, YouTube videos,and obscure news reports to unearth statements by Adegbile's associates that they tied to the nominee and then used to pressure Democrats to oppose him.
His office shared parts of the file with The Inquirer. None of the information they provided cited direct comments or actions by Adegbile. Toomey said Adegbile was responsible for the public comments of his subordinates.
One of the top quotations from the NAACP fund came not from a staffer, but from Adegbile's boss, who called Abu-Jamal's conviction a "relic of a time and place that was notorious for police abuse and racial discrimination." The speaker is not identified in Toomey's dossier.
Another citation is from a 2011 report in the New York Beacon, a small African American weekly newspaper. Under the headline "Innocent Prisoner," it said the NAACP was trying to get Abu-Jamal out of prison - which Toomey's document said explained the defense fund's role.
But that piece of the Beacon story is not attributed to any individual or group, and at that time the only issue being litigated was Abu-Jamal's sentence.
Toomey's file included comments from one of the lawyers Adegbile supervised, Christina Swarns, who attended pro-Abu-Jamal rallies, including one at a street named for him in France. She asserted that race was the reason the "justice system has completely and utterly failed Mumia Abu-Jamal."
Toomey aides distributed the information before a key Judiciary Committee vote, along with a searing letter from Maureen Faulkner, widow of Daniel Faulkner, whom Abu-Jamal was convicted of killing. Toomey sent the letter to Republicans and Democrats before calling them to lobby on the issue, and he armed police unions with the information as they leaned on lawmakers to block Adegbile.
Toomey said he supported the principle that even the worst criminals deserve a fair defense, but that "Adegbile very actively participated in this mockery of our justice system."
Toomey "educated people on who this nominee was," said Don Stewart, deputy chief of staff for the top Senate Republican, Minority Leader Mitch McConnell (R., Ky.). Democrats, Stewart added, "didn't want to be the deciding vote for a guy who was an advocate for a cop killer."
Adegbile's supporters argued that Toomey and Republicans unfairly held him responsible for defending an unpopular figure and said the opponents distorted the nominee's work. Obama called the final vote "a travesty" that "denied the American people a good public servant."
Six hours after the vote, Sen. Tom Harkin (D., Iowa) returned to the Senate floor, visibly angry. A senator since 1985, he called the vote "the lowest point that I think the Senate has descended into in my 30 years here."
Adegbile told lawmakers he only supervised defense fund lawyers who worked on the case. His name appears on three briefs, first in 2008, as lawyers fought over a death sentence that had been dismissed in 2001.
But the broader divisions around Abu-Jamal pushed Casey and Coons to oppose Adegbile, despite his renown as a lawyer who had twice argued voter protection cases before the Supreme Court.
The votes from the two Democrats with close links to Philadelphia proved critical in sinking the nomination in the Democratic-controlled Senate.
"That whole campaign was deeply offensive to me," said Casey, referring to Abu-Jamal's most vocal backers, "and I think it was offensive to folks in our state and beyond." Casey said he had raised concerns privately among Democrats.
Adegbile "obviously had great qualifications," he said in an interview. But he also pointed to the international support that made Abu-Jamal a hero in some corners. "I concluded that a vote in favor (of Adegbile) would validate that."
Coons, of Delaware, lauded Adegbile's "significant and broad career as a leading civil rights advocate." But after supporting Adegbile when he came before the Judiciary Committee, Coons voted against the nominee in Wednesday's key procedural vote.
He cited concerns about Abu-Jamal's celebrity and the reaction from law enforcement. But he also called the vote "one of the most difficult" he had cast.
"As a lawyer, I understand the importance of having legal advocates willing to fight for even the most despicable clients," he said after the vote. "The decades-long public campaign by others, however, to elevate a heinous, cold-blooded killer to the status of a political prisoner and folk hero has caused tremendous pain to the widow of Philadelphia police officer Daniel Faulkner and shown great disrespect for law enforcement officers and families throughout our region."
He said the vote was "more about listening to and respecting their concerns than about the innate qualifications of this nominee."
Staff writer Jeremy Roebuck contributed to this article.