Issa’s aides promptly responded: The remark was over the top, they agreed, according to sources familiar with the interaction.

But Issa himself is unbowed. In an interview with POLITICO, he again accused the White House of being less than truthful on key subjects — while avoiding the word “liar” — and refused to apologize for his Carney broadside…

Top Republicans have privately quizzed Issa’s friends and members of his House Oversight and Government Reform Committee about how exactly Issa could slip up at such an inopportune time.

GOP leaders are concerned that the sometimes unpredictable chairman could jeopardize the biggest gift handed to them in months — public outrage over the IRS scandal, combined with questions over Benghazi. They think Issa should stop personalizing the scandals by insulting Obama and his aides and focus on the facts.