* Today President Obama announced that the number of people getting private health insurance through the exchanges has hit 8 million. And the mix of ages among that group is also encouraging, paralleling the late surge in younger sign-ups we saw with Romneycare. Jonathan Cohn explains everything you need to know about the announcement, including this:

The overall age mix for the Affordable Care Act is virtually the same as the age mix was in Massachusetts. More important, it vindicates the predictions of experts…who said, all along, that young people would be among the last to sign up.

That seven million target may have been arbitrary, which means that eight million is in some way just as arbitrary. Nevertheless, it’s a very big number, representing a lot of people who have an intense interest in the success of the ACA (not to mention the millions more newly insured through Medicaid).

* In his announcement of the new numbers, Obama seemed to be giving instructions to Democrats for how to talk about the issue, and how to hit Republicans over it:

“They still can’t bring themselves to admit that the Affordable Care Act is working. They said nobody would sign up. They were wrong about that. They said it would be unaffordable for the country. They were wrong about that. They were wrong to keep trying to repeal a law that is working when they have no alternative answer for the millions of Americans with pre-existing conditions who’d be denied coverage.”

Keep an eye on whether Dem candidates go a little harder at this kind of messaging in the wake of the announcement.

* Sam Baker, on the 8 million sign-ups:

There are some big unknowns behind that number, but it is nevertheless a hugely positive figure for the White House and Democrats…Some 3.7 million people signed up in March and April alone — more than in the first four months of enrollment combined, and more than double what the Health and Human Services Department had initially anticipated, even though it expected a spike at the end of the open-enrollment window.

The law’s exchanges are now on track to meet coverage targets that seemed wildly out of reach during the disastrous HealthCare.gov launch and were still somewhat unrealistic as recently as last month.

And yet, for many in the political world, we’re still stuck in October of 2013. — gs

* Meanwhile, another GOP Senate candidate, Tom Cotton of Arkansas, dishes up word salad when asked where he stands on his state’s version of the Medicaid expansion. We now have four GOP Senate candidates — Cotton, Thom Tillis, Terri Land, Scott Brown — who are equivocating either on their state’s Medicaid expansion or on repeal. — gs

* And over in Louisiana, video has now surfaced showing Bill Cassidy, who is running to replace Sen. Mary Landrieu, pushing a bill to create a state  health exchange. Socialism!

* The Los Angeles Times reports that the Obama administration is looking at whether immigrants in detention should get bond hearings, which could lead to the release of many now being held. It’s the latest sign the administration may soon roll out executive actions to ease deportation.

* Sean Trende goes through all the competitive Senate races to make the case that Democrats holding on to the Senate is, if not likely, at least possible. A lot of things have to break their way, but it could happen.

* Reality check of the day: Jonathan Bernstein explains why Obama’s approval ratings are likely to remain in the doldrums and remain a drag on Dems. Silver lining: He is unlikely to be as much of a drag on candidates as Bush was in 2006! — gs

* David Firestone details how Democratic Sen. Mary Landrieu is running against the environment, positing herself as the protector of the oil and gas industry in Washington. “Democrats have given her a pass on her self-serving positions. It doesn’t mean, however, that they have to listen to her if she survives.”

* Elizabeth Warren is a straight-talking senator, so you’d expect her new memoir to dish lots of tasty dirt. But Noam Scheiber has a nice catch: Warren recasts the debate over a bank-backed bankruptcy bill in a way much more complimentary to Hillary Clinton than in her previous book. Conclusion: “Until today, I thought there was a small but significant chance Warren would challenge Clinton in 2016. I now think it’s pretty damn close to insignificant.”

* Over at the American Prospect, I wrote about the circle of scam in the conservative media, in which everybody’s making money off everybody else, except for the rank-and-file folks whose donations and attention power the whole thing.

* Astronomers have discovered what they call the most Earth-like planet ever identified. Except there, all campaigns for office are polite and substantive, and there are no political TV ads. Horrifying!

* And the tweet of the day, from the NRCC:

@NRCC: No, we can’t. RT @ZekeJMiller: Obama:  “I think we can all agree that it’s well past time to move on.”

No, they really can’t, but a majority of Americans can. — gs