* David Roberts has a useful explainer on why today’s news about the EPA’s new rules on mercury and other toxic emissions is such a big deal.

* Senate Dems debut a new talking point on the looming expiration of the payroll tax cut: “Boehner tax hike.”

* The Post editorial board clarifies just how catastrophic the consequences of failing to reach a deal, and failing to extend unemployment benefits, would really be:

This is cruel and unwarranted at a time when there are about four jobless workers for every available position and two-fifths of the unemployed have been looking for work for more than six months. If the benefits are not extended, about 1.3 million people will lose coverage in January alone.

The Senate has passed a measure with overwhelming bipartisan support that would avert this; the President is prepared to sign it; and conservative opinion-leaders are increasingly acknowledging that it’s the only way out. The only holdouts against the two-month compromise at this point are the House GOP’s “Bravehearts.”

* To press that point, Senate Dems have released a new video compilation of Senate Republicans battering their House counterparts on the issue and urging them to embrace the inevitable.

* Mitt Romney refuses to say whether he thinks House Republicans should pass the Senate payroll tax cut extension, the latest in a long run of equivocations on the issue.

* Unlike Romney, Newt Gingrich is willing to take a stand on the most important political impasse of the moment: He says House Republicans should give in.

* Karl Rove concurs, telling House Republicans it’s time to accept the inevitable, because they’ve already “lost the optics on this.” Video of Rove is right here.

* Not sure they’re going to take Rove’s advice, though: A well placed GOP source tells CNN’s Dana Bash that House Republicans plan to take this one down to the wire.

* But ABC’s Jon Karl reports that Republicans are looking for a way out:

Republicans are now searching for a face-saving way to give up. The most likely scenario would be for Democrats to agree to negotiations on a full-year extension to begin as soon as next week — but only after the House passes the two-month extension.

Which is close to what Dems have already offered. Jed Lewison predicts that Republicans will cave and “define doing what Democrats want as victory.”

* Chart of the day: Jared Bernstein’s inequality dragon, neatly demonstrating that

“Corporate profits have not only recovered their post-recession highs, they’ve surpassed it. And compensation as a share of the economy is far lower.”

* Yes, people really don’t like health reform’s individual mandate, but a new poll finds their opinions begin to change when they’re told the truth about it.

Key takeaway: The extent to which misinformation, distortion and outright lies helped cause the unpopularity of health reform still has yet to be appreciated.

* Massachusetts Dems plugging for Elizabeth Warren are getting increasingly aggressive about using Mitt Romney against Scott Brown, labeling Brown’s sudden new populism a “Romney-style reinvention campaign.”

* And it’s gettin’ hotter: After Romney refuses to condemn the pro-Romney Super PAC’s negative ads attacking Gingrich, claiming Newt can’t take the “heat,” Gingrich issues Romney a challenge: Debate me in Iowa, one on one, 90 minutes, no moderator.

Says Gingrich: “Let’s test this kitchen.” Not gonna happen, for obvious reasons.

What else is happening?