Six states are in the process of shifting to state marketplaces in hopes of achieving cost savings, improved customer experience and greater control over health care plans. (Photo: Getty)

Just as a number of states that previously declined federal funding to expand Medicaid have since reversed, some state governments are beginning to assume greater oversight of their state's health care marketplace.

When the Affordable Care Act was launched six years ago, states had a decision to make: Would they set up their own insurance marketplaces or would they leave that to the federal government?

Originally, only 17 states set up their own marketplaces. In the following years, some retreated and handed off control to the feds. Now, only 11 states and the District of Columbia operate their own insurance exchanges, according to an analysis from the Robert Wood Johnson Foundation.

Related: New 'super broker' system cuts HealthCare.gov out of the ACA signup process

In many cases the decision to use the federal marketplace had as much to do with politics as policy: Republicans, who were in control of most state governments, viewed setting up their own exchange as an endorsement of the ACA.

It also isn't all-or-nothing. There are currently only 17 states that have relinquished entire control of their marketplaces to the feds.

Another 17 states have "State Partnership Marketplaces" where the state oversees management of insurance plans and provides customer assistance but the feds are in charge of all remaining functions. Five states have "State-based Marketplace-Federal Platforms," (SBM-FP) where the state is responsible for administering the marketplace but customers enroll in plans via the federal HealthCare.gov.

Now, six states are in the process of shifting to state marketplaces in hopes of achieving cost savings, improved customer experience and greater control over health care plans.

Maine, New Jersey and Pennsylvania are transitioning from marketplaces that are entirely operated by the feds to SBMs. They plan to complete the transition for the 2021 plan year.

Nevada, New Mexico and Oregon are switching from SBM-FPs to SBMs. Nevada will switch for the upcoming 2020 plan year, while New Mexico is planning to switch by the 2022 plan year. Oregon's timeline remains up in the air.

Some of these changes are due to a shift in political control. Maine, New Jersey, New Mexico and Pennsylvania had Republican governors during the implementation of the ACA but now have Democratic governors, although Pennsylvania still has a GOP-controlled legislature.

Nevada and Oregon originally put in place state-based marketplaces but relinquished control due to technical issues. Now both states are going to give SBMs a second try.

The election of Donald Trump has given Democratic state governments an additional incentive to take over. The Trump administration has sought to undermine the ACA by reducing the enrollment period and cutting funding for the marketing of the marketplace.

Read more:

• Data breach stalls HealthCare.gov's direct enrollment system
• CMS star rating plan expanding to all ACA exchanges
• 5 states of 2017 ACA exchange rate data