So this afternoon, Mitch McConnell made the most specific "fiscal cliff" offer we've seen thus far from Republicans. Here it is:

In an interview in his Capitol Hill office, Mr. McConnell said if the White House agrees to changes such as higher Medicare premiums for the wealthy, an increase in the Medicare eligibility age and a slowing of cost-of-living increases for programs like Social Security, Republicans would agree to include more tax revenue in the deal, though not from higher tax rates. [...]

Mr. McConnell offered his ideas as examples of the structural changes Republicans are looking for. "The nexus for us is: revenue equals genuine entitlement eligibility changes," Mr. McConnell said.

McConnell's offer is this: We'll give you increased revenues via the closing of loopholes -- and in exchange, you give us the entitlement reforms we want, plus the tax rates we want.

That's not much of a compromise. Indeed, it's not new. As Steve Benen noted recently, that essential arrangement is what Lindsey Graham offered last Sunday.

In fairness to McConnell, the White House has not offered a compromise either. It has laid down what it wants and offered a small concession in the form of Medicare cuts. McConnell has now done roughly the same: He has laid out what Republicans want in entitlement reform and made a small concession in the form of revenue increases. To be clear, this is what McConnell should be doing. This isn't as specific as we need it to be, but it's sort of a start. We want Republicans to tell us what they want; they're not obliged to offer a "compromise" up front either. What remains to be seen is whether the same pundits who criticized the White House offer as "unserious" because it doesn't contain significant concessions will dismiss McConnell's offer in similar terms now that he has done precisely the same thing.

That aside, what to make of McConnell's offer? Liberal-leaning analysts believe raising the Medicare eligibility age would adversely impact hundreds of thousands of seniors and wouldn't raise as much money as advertised. A recent study by the Center for American Progress found that it would result in about 270,000 seniors being uninsured, and many others paying higher premiums. Topher Spiro, a health care analyst at CAP, notes that by taking out the younger seniors, you leave behind an older and sicker pool that ends up paying higher premiums, because their health care costs are higher. And he notes that many seniors left without Medicare would go into Medicaid or into the Obamacare exchanges, offsetting the federal savings from raising the eligibility age. Because of this, the Congressional Budget Office recently estimated that this move would save $125 billion over 10 years.

What about the revenue side of McConnell's offer? Without more specifics in terms of how McConnell would raise revenues, it's very hard to evaluate how much it would bring in. "It's impossible to estimate how much revenue McConnell's plan would bring in without knowing which tax loopholes he would go after and which taxpayers he would target," Roberton Williams, a senior fellow at the nonpartisan Tax Policy Center, tells me.

And so here's where we are: Democrats are willing to give on Medicare cuts, though not by as much as Republicans want. Meanwhile, Republicans won't give any ground on the core concession they need to make -- on tax rates for the rich -- though they want you to think they're flexible because they're willing to agree to higher revenues, in unspecified amounts. We're pretty much back where we started.