Gallup just released new data showing the percentage of uninsured Americans continues to fall, though it’s too soon to tell whether it’s because of Obamacare:

The percentage of uninsured Americans fell to 16.0% so far in the first quarter of 2014 from 17.1% in the fourth quarter of 2013. […]
The uninsured rate also dropped to the low-16% range in late 2012 before rising again in 2013, suggesting that there may be inherent variability in the rate or random fluctuation due to sampling error.
Still, if the uninsured rate continues to fall over the next several months, it may suggest that the Affordable Care Act’s requirement for most Americans to have health insurance, which took effect on Jan. 1, is responsible for the decline.

Gallup regularly releases findings on the percentage of uninsured, and as Jonathan Cohn explained the last time Gallup put out data showing a drop, you should treat it with skepticism, because it could reflect statistical volatility.

Still, today’s survey expands on the last one, and now that it, too, has confirmed this drop, it’s cause for a bit more optimism that it is real, though caution is still in order, and we still can’t be certain Obamacare is the reason for it.

According to Larry Levitt of the Kaiser Family Foundation, the drop may be directly relevant to the big political debate over cancelled policies — and to the claim by some foes that this could lead to a net drop in those covered.

“It’s an early possible sign of success,” Levitt told me. “There’s been a lot of uncertainty about the affect the ACA is having on the number who are uninsured. Clearly people are signing up, and clearly Medicaid coverage is expanding. But many had their policies canceled. This is the first sign that the net of all that is still likely a decrease in the number of uninsured — it may be moving in the right direction.”

Still, Levitt added: “I would emphasize that it’s noisy.”

And so it’s still too early to know how much this matters for the law’s long term prospects, let alone for the politics of the law, which will likely continue to be tough going for Democrats.

However, the Gallup numbers remind us that we’re inexorably moving into the realm of the concrete when it comes to the most important Obamacare metric of all — how many people are gaining heath care coverage. The Beltway argument is consumed with other concerns: how much of an impact the employer mandate delay will have, and whether Republicans can capitalize on it; whether Dems are “running away” from the law; and what the CBO report said about its economic impact.

But the CBO report also found that the law is on track to come close to its enrollment targets. And as Gallup notes today, we could also see a continued decline in the percentage of uninsured, and that will suggest Obamacare is the cause of it. The point is, we are slowly going to be gaining more and more concrete information to gauge whether it is fulfilling its core goal.

If the information suggests that is indeed what is happening, the politics of Obamacare could also get harder for Republicans. They will no longer be able to take refuge in the hypothetical and will have to reckon with the actual impact their position (whether full repeal or a GOP alternative) would have on what the health system is becoming, and what that means for untold numbers of people.

“We’ve been fighting about this law in the realm of  speculation for years,” Levitt says. “What we should be looking at primarily is, are more people getting covered? That’s the law’s fundamental aim. We will now start to see real data.”