REUTERS/Kevin Lamarque

About two hours into lawmakers' grilling of Mary Barra on Tuesday, Rep. Peter Welch (D-Vt.) looked at her and told the General Motors chief executive: "You are the company right now."

As if she didn't know. Barra, a GM lifer who became CEO less than three months ago, is in the wholly unenviable position this week of answering questions from both houses of Congress over the company's slow response to an ignition switch flaw that led to the recall of 2.6 million vehicles and has been tied to at least 13 deaths. Her first test — Tuesday's appearance before the House Energy and Commerce committee — resulted in repeated deflected questions, multiple apologies and a general sense that, beyond the hiring of victims' compensation expert Kenneth Feinberg, we weren't going to learn much that was new.

And yet, it's hard to say Barra did poorly in her debut on the Congressional hearing stage, either. She didn't squirm. She came across as calm and contrite, committing no obvious gaffes. She was willing to speak with reporters after the hearing — an unusual step for a CEO under this much scrutiny — which seemed to project confidence and some candor, even if she didn't stray much from her scripted remarks.

And she didn't get pulled into a heated debate with grandstanding politicians, even those clearly looking to bait her with soundbites.

Yet Barra needed to be more than just unflappable. She needed to be convincing. She talked about how the new GM had been going "from a cost culture, after the bankruptcy, to a customer culture," adding the first company-wide head of safety, taking out a layer of management and modeling the right leadership behaviors from the top.

But lawmakers understandably found some of those changes to be lacking. For instance, Rep. Jan Schakowsky (D-Ill.) said she was "underwhelmed" by the naming of the company's first company-wide product safety chief. As a car company, it's much more surprising that General Motors didn't have one before than that they do now. And after Barra said the company had changed its core values, Rep. Ben Braley (D-Iowa) asked her whether safety hadn't always been one of the the company's "core values." If safety wasn't one of them, what was?

It's tricky for CEOs to be persuasive when they've been coached and rehearsed to the point that their repetitive answers make them sound like a broken record. A legal morass this complex unfortunately places limits on the language any corporate lawyer is going to let a CEO use. It was easy to lose count of how many times Barra referred to not knowing certain things, or to finding past actions at the company "unacceptable," or to waiting for the investigation's results to be completed.

That may have rankled lawmakers, the public and, quite understandably, the families of the victims. And we won't really be able to judge Barra's performance until we find out how well her narrative holds up once the findings by Anton Valukas, the former U.S. attorney doing the investigation she repeatedly mentioned, are revealed to the world.

But despite how frustrating the script may have been to many, Barra turned in a performance that would likely get corporate damage control expertsapproval. The Congressional hearing is political theater, and success on this stage is measured less by rave reviews and more by a corporate version of the Hippocratic oath — first, do no more harm.

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