Saying ties to the country's "most notorious cop-killer" was a question of professional fitness, Senate Republican Leader Mitch McConnell, R-Ky., led the way to defeating a key Obama nominee on Wednesday.It marks the first time one of the president's appointments has failed to move through the Senate since Democrats changed the rules last year to overcome McConnell's effective filibusters.Seven Senate Democrats joined the GOP caucus to block Debo Adegbile from heading up the Justice Department's Civil Rights Division. Adegbile previously worked as a defense attorney for Mumia Abu-Jamal, a former Black Panther who was convicted of killing Philadelphia police officer Daniel Faulkner over three decades ago.Speaking on the Senate floor, McConnell cited a number of of law enforcement agencies who objected to the nomination."The National Fraternal Order of Police wrote President Obama to express its 'vehement opposition to the nomination.' The FOP wrote that ‘as word of this nomination spreads through the law enforcement community, reactions range from anger to incredulity,’ and that it ‘can be interpreted in only one way: it is a thumb in the eye of our nation’s law enforcement officers,'" he said."The Kentucky Narcotic Officers’ Association wrote me a powerful letter in opposition to the nomination as well. In it, they note that, 'The thought that [the nominee] would be rewarded, in part, for the work he did for Officer Faulkner’s killer is revolting."Adegbile helped overturn Abu-Jamal's death sentence six years ago as part of the NAACP's Legal Defense Fund. In that case, a judge found merit in a case presented by Abu-Jamal's attorneys, who argued he faced a discriminatory jury.The racially charged case has been a controversial 30-year legal battle with law enforcement groups and Faulkner's family on one side and international human rights activists on the other. The latter argues Abu-Jamal, who is African-American, was unfairly convicted and framed for the killing due to his race.In a statement, President Obama denounced the Senate for its "character attacks" on Adegbile for his legal representation.From The White House: