The analysis comes one day before the deadline when states must decide if they will run their exchanges, partner with the federal government or cede the task to the Department of Health and Human Services entirely.
By Avalere's count, only 17 states have committed to running their own exchanges, a sign that opposition to the Affordable Care Act remains strong among many governors.
Avalere also said that 10 states have refused to expand Medicaid under the healthcare law.
Because most are also defaulting to federally run exchanges, "the portion of exchange enrollees buying insurance through federally administered exchanges could continue to rise," the firm wrote.
See maps below, courtesy of Avalere.