Today’s elections will decide if 4.5 million people get health insurance

For millions of uninsured Americans, this 2014 mid-term election is absolutely about Obamacare. These are the people who live in the 23 states that have not yet signed onto the Medicaid expansion — and where it’s completely up to their elected officials whether or not that will happen in the future.

The Kaiser Family Foundation estimates that 4.5 million Americans currently fall into the “coverage gap”: they don’t earn enough to qualify for subsidized private coverage but, because their state hasn’t expanded Medicaid, they don’t qualify for the public insurance program. You can see those states in the map below: the ones in light grey have decided not to expand Medicaid and those in black are still debating the issue.

It is largely up to people who are elected today in those states whether or not to change that. State legislatures and governors have complete power over the decision for whether to participate in the Medicaid expansion.

Of the 23 states that have not expanded Medicaid, 15 have governors who are up for election. Six of those states have close races that Real Clear Politics describes as toss-ups.

Change could be immediate in a state like Maine, where Democrats already control the state legislature. If Democratic candidate Michael Michaud wins this especially tight race, he’s repeatedly committed to expanding Medicaid in the state. That would bring affordable coverage to an estimated 24,000 Maine residents.

Other places might move more slowly. Florida, for example, is one of the largest states that hasn’t expanded Medicaid. More than 700,000 people there fall into the coverage gap. And even if Democratic candidate Charlie Crist wins, he would still be working with a Republican legislature that has opposed previous Medicaid expansion attempts. But Crist has said he would consider expanding Medicaid by executive order, essentially working around the legislature.

The other competitive governors races in non-Medicaid expansion states — in Alaska, Georgia, Kansas, Maine, New Hampshire, and Wisconsin — are all places where Republicans control the legislatures. They’re less likely to move quickly on implementing the major Obamacare program.

And that underscores why the state legislative races happening today matter so much, too. Governors have generally been hesitant to expand Medicaid without the support of their statehouse (there are exceptions, such as Ohio Gov. John Kasich, who controversially used an executive order to do so).

Much less polling and forecasting happens for state legislative races, so it’s hard to know whether the statehouses in the 23 non-expansion states will become more hospitable to Medicaid. But all of them have elections happening today that matter so much for the future of Obamacare and for who ultimately gets coverage.