WASHINGTON -- The US National Highway Transportation Safety Administration has two weeks to respond to a new series of questions from US Sen. Chuck Grassley (R-IA) regarding Toyota's sudden unintended acceleration (SUA) problems.

The latest queries stem from a new interest in the possibility that tin whiskers may have contributed to the malfunctions, according to CNN reports.

Sen. Grassley, in his capacity on the Senate Judiciary Committee, submitted the queries to the NHTSA following unidentified whistle-blowers who reportedly provided new documentation to the Committee.

Earlier findings by the NHTSA, which relied heavily on NASA for its investigation, seemingly absolved Toyota's electronics systems of blame, citing driver error and improperly installed floor mats among the reasons for the large number of crashes.

However, printed circuit board experts have jumped on those findings, arguing that tin whiskers are difficult to pinpoint because they burn up, and that the NASA findings that indicated the possibility of tin whiskers as a contributing factor were glossed over by the NHTSA.

Toyota denied the new claims, saying that "tin whiskers are not a new phenomenon and do not represent a mysterious or undetectable problem in a vehicle's electronics," told CNN reported.

Grassley requested the NHTSA response by July 26.