The McCain camp’s pushing this out as evidence that Joe the Plumber’s fears are already being realized:

Because you’re successful, you have to pay more than everybody else? We all live in this country. It’s a basic right. And Obama wants to take that basic right and penalize me for it, is what it comes down to. That’s a very socialist view and it’s incredibly wrong. I mean, $250,000 now. What if he decides, well, you know, $150,000, you’re pretty rich, too. Let’s go ahead and lower it again. You know it’s a slippery slope. When’s it going to stop?

Watch the clip, then read on.

Has The One already slid down the slope? Seems like it, says Byron York, flagging the campaign’s new ad for yet a third figure: $200,000 a year, which Obama now claims is the threshold for tax cuts for families under his plan. On the stump today, McCain chipped in with this:

Senator Obama has made a lot of promises. First he said people making less than 250,000 dollars would benefit from his plan, then this weekend he announced in an ad that if you’re a family making less than 200,000 dollars you’ll benefit — but yesterday, right here in Pennsylvania, Senator Biden said tax relief should only go to “middle class people — people making under 150,000 dollars a year.” It’s interesting how their definition of rich has a way of creeping down. At this rate, it won’t be long before Senator Obama is right back to his vote that Americans making just 42,000 dollars a year should get a tax increase. We can’t let that happen.

What’s the deal? From what I can tell, this is a case of Team Barry being characteristically slippery in getting out their message. The One likes to emphasize how only people making more than $250K will have their taxes raised, but that doesn’t mean that everyone making less than that will have their taxes cut. There’s a middle segment, between $150K and $200K for individuals and $200K and $250K for families (as I understand it and as NBC understands it), whose taxes will stay the same, which means Biden is technically correct in the clip. Obama actually mentioned the $150,000 figure back in June in an interview with Fox News, but he prefers to throw around the number $250,000 doubtless because casual observers will assume that’s the threshold for tax cuts. It isn’t. It’s the threshold for tax hikes, and only for families, not individuals. Or so I deduce.

Have The One and his surrogates in fact lied about the tax hike/tax cut distinction in his plan? Saith the RNC’s oppo research team, you betcha:

In July 2008, Barack Obama Said: “If You Make $250,000 A Year Or Less, We Will Not Raise Your Taxes. We Will Cut Your Taxes.” (Barack Obama, Remarks, Powder Springs, GA, 7/8/08)

In August 2008, Obama Economic Policy Adviser Jason Furman Said That Barack Obama “Would Cut Taxes For Almost All Of The Families Making Less Than [$250,000].” FURMAN: “Finally, and perhaps most importantly, the op-ed today makes a very important point that, while Barack Obama would not raise taxes for any family making below $250,000 — in fact, it would cut taxes for almost all of the families making less than that — Senator McCain cannot make a similar promise for his tax plan because, for the first time in history, he would make families pay taxes on the health insurance that they get from their employers.” (Obama For American, Press Conference Call, 8/14/08)

In October 2008, Governor Ted Strickland (D-OH) Delivered The Democrat Radio Response Saying That Those Making Less Than $250,000 Would See Lower Taxes. “He’ll restore the middle class by cutting taxes for small businesses, and for 95 percent of workers and their families, including 5.7 million in Ohio. If you make less than $250,000, you won’t see your taxes go up one single dime. In fact, your tax rates will be lower than they were under Ronald Reagan.” (Governor Ted Strickland, Democratic Radio Response, 10/4/08)

One fact not in dispute: If you make more than $250,000 a year, your capital gains rate is going up, a prospect that’s already having real-world consequences. Here’s Cavuto taking it to Kelly nemesis Bill Burton on the subject yesterday. Just what the doctor ordered with the stock market already off 40 percent since last year: A disincentive for large investors to jump in.

Update: Ambinder has the same numbers I do.