Iowa governor Terry Branstad has now become the fifth GOP governor to vow that his state will not opt in to the Medicaid expansion in the wake of the Supreme Court ruling. He joins the ranks of Louisiana’s Bobby Jindal, Florida’s Rick Scott, South Carolina’s Nikki Haley, and Wisconsin’s Scott Walker.

It’s worth keeping a running tally of how many people could go without insurance that would otherwise be covered under Obamacare if these GOP governors make good on their threat.

The latest rough total: Nearly one and a half million people.

As Sarah Kliff noted the other day, the Kaiser foundation has done a state by state analysis meant to gauge how many people would gain coverage under the Medicaid expansion that didn’t have coverage before. Keeping in mind that this study was performed in 2010, and that these are estimates, here's how many people we’re talking about in each state:

* Iowa: 74,498

* Louisiana: 277,746

* Florida: 683,477

* South Carolina: 247,478

* Wisconsin: 127,862

The approximate total now, according to Kaiser’s numbers: 1,411,061.

Now, in fairness, as Kliff notes, some of these people might be able to get insurance via other provisions in Obamacare, such as subsidies for buying insurance on the exchanges. On the other hand, Kaiser estimates that if states practiced aggressive outreach on the Medicaid expansion, even larger numbers of people than the above tallies suggest could get coverage under the provision. But again, Kaiser’s numbers are estimates.

Of course, it’s still unclear whether these governors will go through with their threats. David Dayen and Ed Kilgore have both been making good cases that they will. As Dayen and Kilgore both note, some of these GOP governors are relying on objections to the cost of the program to the states — even though the federal government covers 100% of the program for the first three years and it remains a good deal beyond — to mask ideological reasons for opting out. The opportunity to play to a national conservative audience, or to strike a great blow against Obama’s signature domestic initiative and against the welfare state in general, must be awfully tempting. Dayen rightly notes that the media will probably fail to sufficiently untangle the cover stories these governors are using.

It seems to me that it makes sense to assume the worst about what will happen in the long run. And the mounting numbers of people who might go uninsured as a result of these crusades is alone a reminder that the Medicaid ruling is the most consequential news coming out of the decision — and of the need to bear down hard on the specifics of what it means.