Sen. Pat ToomeyPatrick (Pat) Joseph ToomeyTop GOP candidate drops out of Ohio Senate race Newly declassified memos detail extent of improper Obama-era NSA spying Overnight Tech: FCC won't fine Colbert over Trump joke | Trump budget slashes science funding | Net neutrality comment period opens MORE (R-Pa.) on Thursday celebrated this week's defeat of a top Obama nominee during a speech to the Conservative Political Action Conference (CPAC).

Toomey led the charge against confirming Debo Adegbile as assistant attorney general for the Department of Justice's Civil Rights Division because of his work on a past case for the NAACP. The push led to the first rejection of an Obama nominee since Senate Democrats changed filibuster rules on nominees, lowering the threshold to 51 votes.

"I knew I could not let that stand without a fight," he said.

Toomey fought hard against Adegbile's nomination because, as a lawyer with NAACP Legal Defense Fund, Adegbile helped work on a Supreme Court appeal for Mumia Abu-Jamal, who was convicted three decades ago of killing a Philadelphia police officer. Abu Jamal's case has drawn international attention — many have questioned whether he received a fair trial or whether the judge and jury were biased against Jamal for racial reasons, which was what Adegbile was questioning as an attorney in the Supreme Court appeal.

"This is not at all about the principle that every defendant deserves a competent attorney," he said. "This was always about the principle that no one should be able to make a mockery of the criminal justice system, fan the flames of racial strife in America, join a dishonest international anti-American campaign, along the way drag the family of a fallen police officer through three decades of hell and then be confirmed to a high post of the Justice Department."

The Senate on Wednesday rejected Adegbile after a number of red-state Democrats, some facing reelection, broke with their party. 

Toomey joked that when Vice President Biden walked into the Senate chamber, it was the "best news I'd had in a month" because that meant Democrats weren't sure they would have the votes to confirm him.

Democratic Sens. Mark Pryor (Ark.) and John Walsh (Mont.), both facing tough 2014 races, voted against confirming Adegbile, as did red-state Democratic Sens. Heidi Heitkamp (N.D.), Joe Manchin (W.Va.) and Joe Donnelly (Ind.).

Sens. Chris Coons (D-Del.) and Bob Casey Jr. (D-Pa.), both of whom represent populations living in the greater Philadelphia region, also voted against Adegbile.