At the end of a long, combative day of testimony before the Republican-controlled House Judiciary Committee, California GOP Rep Darrell Issa compared Holder to disgraced Nixon-era Attorney General John Mitchell.

Holder shot back by comparing Issa to Sen. Joe McCarthy, the infamous Wisconsin Republican censured by the Senate in 1954 for leading what critics called a Communist witch hunt.

"As they said in the McCarthy hearings, have you no shame?" asked Holder, referencing a famous retort to McCarthy.

Holder acknowledged mistakes were made, but said he would not resign over the controversy. The attorney general, accusing the GOP of playing political games, also he also didn't think any of his top aides should step down.