States that have already taken steps to set up health exchanges are running into challenges in building the computer systems that will handle enrollment in 2014. If the computer systems fail the final tests leading up to 2014, states may have to switch to a “partnership” exchange model with the Department of Health and Human Services running key functions. Estimates from health consultants put fewer than a dozen states will be running fully state-based exchanges at first. Deloitte Consulting, which is working on exchanges in multiple states, counts less than 10 states that have finalized contracts with vendors to build the computer systems. This complication could be very problematic for states waiting until the last minute to set up their exchanges.