That's measured by the fundraising totals of Obama, McCain, and the national party convention committees--counting the $84.1 million in federal money McCain received under the public funding program and the $16.8 million the government shelled out for the Democratic and Republican conventions.
See a .pdf of the spending breakdown here.
This article available online at:
http://www.theatlantic.com/politics/archive/2009/06/the-18-billion-election/18960/
