Lawyers for a former in-house attorney at Toyota Motor Sales USA Inc. have moved to withdraw as counsel in a lawsuit that officials in Congress have reviewed in their investigation into recalls attributed to unintended acceleration in Toyota vehicles.

Jeff Allen and Joseph Wohrle, both partners of Allen + Wohrle, a firm in Santa Monica, Calif., filed the withdrawal motion on Thursday. Allen, in a separate declaration attached to the motion, said that a “breakdown in the attorney-client relationship” has made it “unreasonably difficult” to represent Dimitrios Biller. “The present motion to withdraw as counsel of record is necessary because we have been unable to obtain and file an executed version of the Substitution Form I prepared and sent to Biller, and because of the breakdown in the attorney-client relationship which has occurred between our firm, its attorneys, and Biller,” Allen wrote in the declaration.