Congress has so far held three hearings on the Internal Revenue Service's targeting of conservative groups. And, all of those hours can be summed up in just four words: "I didn't do it."

Those words were, of course, made famous by one Bart Simpson, the mischievous little boy on the greatest show ever.

(AP Photo/Fox)

The mantra we've heard time and again from top current and former IRS personnel over the past week has sounded a lot like, well, "I didn't do it." Apologies have ranged from qualified to nonexistent, while lawmakers' allegations of wrongdoing have been met with stiff pushback.

Let's start with Lois G. Lerner, the head of the agency's tax-exempt division, who first revealed publicly that the IRS was singling out conservative groups.

"I have not done anything wrong," Lerner said at a Wednesday congressional hearing. Then, she announced that she would invoke the Fifth Amendment and decline to answer any questions. So, okay.

And former IRS commissioner Douglas Shulman?

"I don’t take personal responsibility for there being a list with criteria put on it, but I do accept the fact that this did happen on my watch," he said Wednesday, adding: "I’m very sorry that this happened while I was at the Internal Revenue Service."

What about recently ousted acting commissioner Steven T. Miller?

"First and foremost, as acting commissioner, I want to apologize on behalf of the Internal Revenue Service," Miller said last week.

Apologize for what?

"For the mistakes that we made and the poor service we provided," Miller continued, adding later: "I can say generally, we provided horrible customer service here. I will admit that. We did horrible customer service."

As The Fix boss wrote on Wednesday, an “every man (or woman) for themselves” mentality may be taking over here. Lerner, Shulman and Miller have each presented carefully prepared arguments for why they shouldn't be blamed, or why the entire episode amounted to bad service as opposed to "targeting."

Herein lies a problem for President Obama: Bad "customer service," non-apologies, and pleading the Fifth mean nobody at the IRS has raised a hand to absorb the brunt of the blame. When it comes to scandals, the public needs to see a fall guy (or girl) before any kind of closure can be achieved. Heads rolling and that sort of thing. Sure, Obama demanded and received the resignation of Miller. But Miller and his former colleagues have been none too keen on becoming public scapegoat No. 1.

And until/unless someone does, the president will continue to face heat from Republicans and scrutiny from the media, even though, as the White House has repeated over and over, Obama didn't even learn anything about the targeting effort until it was reported in the news on May 10.

If someone at the IRS does eventually decide take the blame, they will instantly become a magnet for political criticism. Would Republicans stop slamming Obama at that point? No. But the accountability would allow the president to more effectively push back and argue that (1) the responsible party lies within the agency, not the White House, and (2) the question of "who?" has been answered.

But if "I didn't do it" continues to be the refrain of choice, riding out this scandal could become increasingly unpleasant for the president.