WASHINGTON - Toyota Motor Corp. has put more effort into containing the damage to its reputation than checking all the possible causes of unintended acceleration, a Michigan congressman said Thursday during a contentious hearing on Capitol Hill, The Detroit News reported.

Lawmakers also charged that Toyota was trying to discredit critics and hadn't thoroughly investigated whether its electronic systems might be defective.

The Japanese automaker, struggling with the biggest crisis in its recent history, maintains that it has not discovered any electronic cause for the incidents of unintended acceleration that led to its largest U.S. recall.

Rep. Bart Stupak, D-Menominee, chairman of the House Energy and Commerce Committee's oversight panel, accused Toyota of focusing more on "damage control" than on searching for defects. Toyota has recalled more than 8.5 million vehicles worldwide, including more than 6 million in the United States.

Committee staffers said Toyota had hired the Benenson Strategy Group to conduct a poll about "what Toyota could do to repair damage to the company's image among educated consumers known as 'opinion elites.'"

Toyota, "like most organizations, conducts regular public opinion research," the company said in a statement.

"We are making a major scientific effort to further validate the safety of our vehicles by opening up our technology to an unprecedented level of independent review," Jim Lentz, president of Toyota Motor Sales USA, told the committee.

Committee Chairman Rep. Henry Waxman, D-Calif., said there was "no evidence that Toyota has done extensive or rigorous testing of its vehicles for potential electronic defects that could cause sudden acceleration."

The committee has met with Toyota engineers in Japan and taken their depositions and one from a senior U.S. employee.