With the employer mandate already put on ice, delaying the exchanges would leave only one of the law’s key components intact, the individual mandate.

(Reuters) — Two U.S. government officials warned on Wednesday that the launch of new state healthcare exchanges could potentially be delayed, raising further doubts about the implementation of President Barack Obama’s signature legislation.

Alan Duncan, an auditor with the Treasury Inspector General for Tax Administration, an Internal Revenue Service agency that monitors performance, said testing the systems needed to implement the exchanges “will be difficult to complete” by the October 1 start date.

“The lack of adequate testing could result in significant delays and errors in accepting and processing … applications for health insurance coverage,” he told the House of Representatives Oversight and Government Reform committee.

At the same hearing, Government Accountability Office official John Dicken said the amount of work the federal government needs to do in each state has yet to be determined, raising the risk of missing deadlines. He added that the federal government and the states have already missed some deadlines.