Votes at union locals in six Chrysler plants in Indiana and Michigan in the next two days will be crucial in determining whether the US carmaker succeeds in securing a new four-year contract with its workers.

Chrysler, majority-owned by Cerberus Capital Management, is facing unexpected opposition from the rank and file of the United Auto Workers, whose president, Ron Gettelfinger, initialled the contract with Chrysler on 10 October.