What's Behind Obama's Anti-Spending Kick?

A new ad by the Obama campaign goes after Sen. McCain and Gov. Palin for their big spending ways.

A Democratic candidate on a Republican candidate for spending? 

Especially a Democratic candidate who, let's face, has a bunch of expensive spending proposals he's not willing to give up, even in the face of mounting deficits.....

Kind of an eye-gouge, right?

Obama aides say that the ad isn't really a new tack -- so forget my headline -- just your basic inoculation ad in response to McCain's debate attacks... as well as the Republican National Committee's independent expenditure spot -- a spot that, sources in both campaigns say, is costing the Republicans $5.2 million this week.

The Obama ad is called "spending spree" and ends with the tag line: "Can we afford John McCain?"