The House Energy and Commerce Committee said GM had submitted more than 200,000 documents on the ignition switches that have led to the recall of 2.6 million autos and are linked to 13 deaths. The panel said the National Highway Traffic Safety Administration submitted about 6,000 documents.
The documents, said Representative Fred Upton, the panel's chairman, "paint an unsettling picture."
On Tuesday, the committee will hold its first public hearing on the recalls.
Upton did not give details on what was "unsettling" about the information his committee received. His statement was accompanied by a memo prepared by Republican investigators.
"Why did GM approve ignition switches that did not meet its specifications for torque performance? What was GM's assessment of the implications for performance and safety," the memo also asked.