According to a tally provided by a Democrat who monitors campaign expenditures in Iowa, Sen. Barack Obama has spent $2.8M on television and radio advertising since June 25, when he first aired two biographical ads in markets across the state. His return on investment is debatable.

Obama's $2.8M traffic total is by far the highest among Democrats.

Former Sen. John Edwards has spent a paltry $23,000. Where Edwards used to lead the state by margins in the high-single digits, he is now locked in a three way race with Clinton and Obama.

But Obama's ad spending has not influenced the preferences of the universe of voters who are generally sampled for surveys. His support has been steady, hovering at around 20 percent since June. Obama's aides contend that conventional polling understates Obama's support, that his strategy and message will bring tens of thousands of new voters to caucus, and that voters in Iowa still don't know enough about him to evaluate him next to Clinton and Edwards.

N.M. Gov. Bill Richardson, who began to advertise on April 20, has spent more than $1.7M. He now polls in the low double digits, up from the high single digits.

Sen. Hillary Clinton has spent about $1.2M. Her first Iowa ad, reinforcing her "invisibles" message, aired in August. Several recent polls gives Clinton a slight edge in the state, although there is, as of yet, no consistent trend in her direction.

Sen. Chris Dodd has spent $739,000, and Sen. Joe Biden has spent about $313,000.

At this point in the 2004 cycle, Edwards had spent the most -- about $806,000, followed by Sen. John Kerry, who had spent $558,000. Gov. Howard Dean and Rep. Dick Gephardt had each spent about $350. Dean wound up spending $3.6M on Iowa media before his third place caucus finish, followed by Kerry, the winner, who spent $3M.

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