So Obamacare enrollments have now hit six million, and with an estimated 3.5 million now eligible for Medicaid, that brings the total to 9.5 million. Supporters of the law, however, are greeting the news with lingering caution about its long term prospects. Liberals such as Jonathan Cohn and Paul Krugman are noting with satisfaction that the law is clearly functioning, but also that there are many unknowns: How many people have actually paid? How many were previously insured? Will marketplaces in the states work over time?

Meanwhile, even as it is now clear the law is more or less on track as intended, GOP certainty in an Obamacare-fueled Senate takeover is only deepening — which in turn is leading Congressional Republicans to ramp up their plans to repeal and replace it with, well, something, once they control both houses of Congress.  David Drucker reports on the latest thinking among Congressional GOP leaders:

The possibility that the Republicans might flip the Senate is influencing House GOP leaders’ decisions as they plot health care strategy for the 2014 campaign and 2015 congressional session, according to GOP members and other Republican sources. A major goal is to place the various current Republican proposals under one health care umbrella, while ensuring that this year’s campaign rhetoric matches next year’s legislative agenda.

In particular, House Republican leaders believe their caucus must have a plan for how to respond after Obama inevitably vetoes a bill that would fully repeal and replace the Affordable Care Act. They anticipate that Americans will demand that something be done to fix a law that voters have never embraced. Following through on these targeted reforms would require negotiations with the White House.

The good news: Republicans now appear to be operating from the premise that Obamacare isn’t going to get repealed, and seem ready to enter into a new phase of negotiating over the law’s future. The bad news: Republicans still seem to think voters will want them to vote on repealing the law in 2015, nearly a year from now.

The truth is, some voters very well may want that, but the vast majority of them will probably be Republicans. The new Kaiser poll finds that only Republicans want to repeal the law, and only Republicans want the debate over the law to continue.

While 53 percent of Americans, and 51 percent of independents, are tired of the debate over the law and want to move on to other issues, a plurality of Republicans (49 percent) want the ACA debate to continue. Meanwhile. 59 percent of Americans, and 52 percent of independents, want to keep and improve the law, and only 29 percent of Americans want to repeal or repeal and replace it. By contrast, 58 percent of Republicans want to repeal or repeal and replace it.

By the way, the Kaiser poll also finds that of those who want to repeal the law, only 11 percent of Americans want to replace it with an unspecified GOP alternative. In short, nobody believes there is any GOP alternative, the best intentions of GOP Congressional leaders notwithstanding.

* MEDIA NARRATIVE ON OBAMACARE IS ALL WRONG: A good New York Times report explains: Now that Obamacare enrollment has hit six million, that is a milestone, but what really matters for whether the law will work over time is how the exchanges and the demographic mix work in individual states. Kaiser’s Drew Altman:

“The whole narrative about Obamacare — ‘Will they get to six million? What is the percentage of young adults going to be?’ — has almost nothing to do with whether the law is working or not, whether the premiums are affordable or not, whether people think they are getting a good deal or not. It’s almost like trying to predict the local weather from national averages.”

Like it or not, as one expert notes in the article, it is probably going to take a few years before we know whether the individual marketplaces are working. Sorry!

* HOW TO UNDERSTAND THOSE 6 MILLION ENROLLMENTS: Jonathan Cohn has a very fair piece reminding us of everything we don’t know about the six million enrollees, suming up the big picture this way:

But it also isn’t hard to find stories of people grateful to get insurance that, for the first time, is available to all Americans regardless of pre-existing conditions. Nor is it difficult to find people grateful that they can finally afford coverage, thanks either to newly expanded Medicaid programs or the financial assistance — worth, in some cases, thousands of dollars a year — through the marketplaces. And the fact that enrollment will probably be close to the original projections suggests that the law is working more or less like it’s supposed to work.

And yet, Republicans continue to proceed from the premise that the law has already proven a catastrophe and that everything we’re seeing now is nothing more than damage control.

* HOW WILL OBAMACARE IMPACT PREMIUMS? Sam Baker has a useful explainer laying out how insurance companies are now moving into uncharted territory in terms of Obamacare’s impact on the health care market, and how this could impact future premiums. Bottom line: The law has cleared some key hurdles, and is more or less functioning, but we just don’t know yet how it will work over time.

* OBAMACARE’S HIDDEN VICTORY: Sophie Novack points out that even the six million enrollment figure might not do justice to the true number of signups, which means a factor that could actually help the law’s prospects over time is not being acknowledged:

As the final figures before the end of open enrollment are posted, a significant chunk of people who bought insurance under the law will be missing from the official tally. That’s because people who bought insurance directly from insurers, and not through the law’s exchanges, will not be included…It’s quite possible this number would more than balance out the premium payment discrepancy—but unfortunately for HHS, we might not know for a very long time.

Did I mention that we just don’t know yet how the law will work over the long haul?

* KEEP AN EYE ON NORTH CAROLINA GOP SENATE PRIMARY: The latest: Heavyweight conservative Senator Mike Lee is campaigning with and raising money for Greg Brannon, the Tea Party candidate who is vying with GOP establishment favorite Thom Tillis to take on Dem Senator Kay Hagan. What to watch for: If neither clears 40 percent in the May 6th primary, there will be a runoff between the top two — which could bring in the big conservative groups and endorsements for Brannon.

Dems are hoping for a Brannon win, which could make it easier to hold Hagan’s seat (and with it the Dem majority), but either way, a runoff would mean Republicans don’t have their nominee until mid July.

* THE HISTORICAL ROOTS OF TAXING THE RICH: Paul Krugman has an excellent column on new research showing that wealth is increasingly concentrated at the top and that taxing the rich explicitly to combat inequality actually has deep roots in the nation’s past going back to the progressive era and beyond:

The demonization of anyone who talks about the dangers of concentrated wealth is based on a misreading of both the past and the present. Such talk isn’t un-American; it’s very much in the American tradition. And it’s not at all irrelevant to the modern world. So who will be this generation’s Teddy Roosevelt?

Meanwhile, even modest efforts to combat inequality look dead in this Congress.

* AND PRESSURE MOUNTS ON OBAMA ON DEPORTATIONS: Benjy Sarlin has a good overview of the situation, talking to immigration advocates who say that if Republicans fail to act, pressure on Obama to move unilaterally to slow deportations will grow overwhelming. Note this, from Frank Sharry of America’s Voice:

“Quite frankly, we expect Obama to act boldly to protect most of the undocumented through executive action. Then we’ll go abut the business of electing a Congress that will pass reform without all these concessions to Republicans.”

One thing to watch for: If Republicans don’t act, and Obama somehow does, you might see advocates then argue that we should wait to act legislatively until Dems control everything, cutting Republicans out of the process.

What else?