NEW YORK (TheStreet) -- Sparks flew at a Senate Commerce Committee hearing focused on whether the National Highway Traffic Safety Administration dropped the ball when it failed to detect defects in the airbags supplied by Japanese auto parts manufacturer Takata

"Now is the time for accountability," said Committee Chairman John Thune (R-S.D.).

The two key points at issue were whether the agency had mishandled its investigation into the defective airbags, and the timing of the automotive recalls that followed.

NHTSA Administrator Mark Rosekind addressed the shortcomings cited in an audit conducted by Calvin L. Scovel III, inspector general of the Transportation Department, which found that NHTSA's staff needed better training and better data collection.

Rosekind admitted the government still doesn't know what caused the airbag defect, and pointed to the agency's limited budget as the reason it was unable to operate more effectively. But several of the senators on the committee did not find that a compelling argument.

"This audit report is the worst that I've ever seen," said Sen. Claire McCaskill (D-Mo.). In her view, she said, the problem at NHTSA isn't a lack of resources, but "blatant incompetent mismanagement." She added that she wasn't comfortable increasing the agency's budget until there was evidence of meaningful reform.

NHTSA said it's addressing all of the issues raised in the audit report, and is already responding to 10 of the 17 major recommendations for improvement.

Starting next week, NHTSA will hold a public hearing to determine whether Fiat Chrysler (FCAU) - Get Report has failed to fix safety defects. Other hearings with other automakers will follow. To date, the Takata airbag recall has impacted nearly 34 million vehicles made by 11 automakers.  Takata's faulty airbags have been linked to eight deaths nationwide.