WASHINGTON -- The president of Toyota's U.S. operations acknowledged to lawmakers on Tuesday that the company's recalls of millions of its cars may "not totally" solve the problem of sudden and dangerous acceleration, according to The Associated Press.

"We are vigilant and we continue to look for potential causes," Toyota's James Lentz told a congressional panel. However, he repeated his company's position that stuck gas pedals in some of the company's most popular model cars and trucks were caused by one of two problems - misplaced floor mats or sticking accelerator pedals.

He insisted electronic systems connected to the gas pedal and fuel line did not contribute to the problem, drawing sharp criticism from lawmakers who said such a possibility should not be ruled out and from a tearful woman who said she had been at the wheel of a runaway Lexus.