UNITED STATES - JUNE 11: Sen. Mark Pryor, D-Ark., heads to the Senate floor for a vote on Wednesday, June 11, 2014. (Photo By Bill Clark/CQ Roll Call)

The Affordable Care Act, in its brief time on this earth, has endured its share of storm and stress. The bungled rollout of the federal online interface cost proponents lots of political capital. There have been high-wire legal challenges to surmount. While public approval of the law's ends remains steadily high, the popularity of the law itself is often recorded as lacking. There have been uneasy periods for Obamacare's chief proponents as they've waited for enrollment milestones to be reached and rate-hike hysteria to be put to bed. (There's recent news on that front, actually.) And as the law promises so much, over such a long time frame, there will be more uneasy periods to endure for the lawmakers who put their stamp on the reform.

But the simple fact is that some lawmakers voted for Obamacare and some voted against it, and there's only so far any of them can run from their decision. That's why I've had the occasion to talk about "the Obamacare bet." The bill's opponents have largely settled on a claim: The law is going to fail and their admonitions against it will be proven wise and correct. The bill's supporters should go ahead and stake the opposite claim. Many of those who supported the bill, however, have been reluctant to go "all in" on the decision they made. Especially among those who voted for the law and have since found themselves in a tough electoral race.

Today, however, comes a change. As Greg Sargent reports over at The Plum Line, Sen. Mark Pryor (D-Ark.) -- currently in a tough re-election race against his Republican opponent, Rep. Tom Cotton -- is up with a new ad in which he heralds his yes vote on the Affordable Care Act. You can watch the spot and read the transcript below. While Pryor doesn't exactly go "all in," he lays more of his chips on the felt.

DAVID: When Mark was diagnosed with cancer, we thought we might lose him. MARK: My family and my faith helped me through the rough times. DAVID: But you know what? Mark's insurance company didn't want to pay for the treatment that ultimately saved his life. MARK: No one should be fighting an insurance company while you're fighting for your life. That's why I helped pass a law that prevents insurance companies from canceling your policy if you get sick or denying coverage for pre-existing conditions.

(David, by the way, is Mark's dad as well as a former senator from and governor of Arkansas.)

Now Mark Pryor's ad could have been a bit bolder. You'll note that nowhere does he say the words "Obamacare" or "Affordable Care Act," just that he "pass[ed] a law." Of course, he does make mention of the law's most popular features -- it prevents people from getting kicked off plans when the time comes to avail themselves of their coverage, and it ends the practice of denying coverage for pre-existing conditions. It's hard to imagine voters tolerating a return to the status quo ante, which is one of the reasons that it's been so devilish for the law's opponents to craft an alternative.

Pryor may have buried the lead in this ad, in fact. As Gallup reported earlier this month, Arkansas leads "all other states in the sharpest reductions in their uninsured rate among adult residents since the healthcare law's requirement to have insurance took effect at the beginning of the year."

Republicans will undoubtedly cast this as an acknowledgment that their attacks on Pryor over the law are working and could no longer be ignored. They’ll argue Pryor is, in desperation, using his faith and personal experience as a shield against those attacks. But this misses what's really going on here. This ad is actually coming at a point where there are signs the anti-Obamacare fires are cooling somewhat. GOP advertising against the law has fallen off sharply, and is surprisingly low in Arkansas.

This is correct. As Bloomberg News' Heidi Pryzbyla reported earlier this week, Republicans have cut way back on on ads that attack Obamacare, in "a sign that the party's favorite attack against Democrats is losing its punch." Pryzbyla continues:

The shift -- also taking place in competitive states such as Arkansas and Louisiana -- shows Republicans are easing off their strategy of criticizing Democrats over the Affordable Care Act now that many Americans are benefiting from the law and the measure is unlikely to be repealed. "The Republican Party is realizing you can't really hang your hat on it," said Andrew Taylor, a political science professor at North Carolina State University. "It just isn't the kind of issue it was."

There is a good reason for this shift. As Matt Yglesias pointed out back in June, the "phony Obamacare debate" -- the one that broadly alleged that death panels existed, that the fubar launch of the federal website was the law's death knell, that enrollment numbers would be way off target -- has run its course, leaving only the most fundamental debate of all:

[Obamacare] is a large-scale effort to improve living standards for people in the bottom half of the income distribution by giving them additional economic resources. One of America's political parties doesn't like that idea in any non-health context and they don't like it for health care either. They think the money it costs to provide those subsidies should be taken away, and it should be given to high-income households in the form of tax cuts. This is an excellent and important policy debate to have. One of the great ideological issues not just of our time and place, but of democratic politics across eras and countries. Should economic resources be distributed more equally or less equally?

Since Yglesias wrote that piece, we've seen a brief return to the "phony" debate, thanks to a pair of judges on the D.C. Circuit appeals court, who issued a ruling in the Halbig v. Burwell case contending that (to quote Simon Maloy in Salon) "a single poorly worded snippet of the Affordable Care Act invalidates subsidies for people who purchased health coverage through the federal exchanges." As Maloy inventively points out, this is a hilariously bad-faith argument to make, akin to George Costanza's "Moops" argument in "Seinfeld":

Beyond that, however, we are ultimately left with the discussion that Yglesias mentions as the real underlying debate: whether it is right and proper to redistribute money from the top to the bottom so that those on the lower rungs of the economic ladder can live and work longer without going into catastrophic debt.

This argument's signature virtue is that -- unlike all the "death panels" and doom-saying -- it is, legitimately, a good-faith argument. Which may cause one to wonder: Why has it taken so long to burn off all the bad-faith arguments and get down to the real bone of contention? I'd posit that arguing that poor people aren't morally fit enough to deserve health insurance lacks a certain salability outside the Ayn Rand set.

With that in mind, you might think it's strange that so many of Obamacare's proponents have seemed reluctant to take "the Obamacare bet." I agree! It's strange. From my perspective, the die has long been cast, so lawmakers who affirmed the bill with their vote may as well own it. Pryor's ad suggests that perhaps those lawmakers long deemed to be vulnerable due to their votes on the Affordable Care Act may be coming around to this position.

None of this should cause you to expect some sort of sea change in the overall fundamentals of the 2014 election. The GOP is still in great shape for the midterms, and they may even discover that they don't need an anti-Obamacare blitz to win in November. But that's really just an even better reason for vulnerable lawmakers who supported the Affordable Care Act to put some sustained ballyhoo behind their decision to vote for the law. Win or lose, may as well remind people where you stood. Pryor's effort is a lot bolder than most.