Senator Barack Obama wants voters in Texas and Ohio to vote early, and his campaign is running huge video-enabled billboard ads to promote the convenient option. Yet, despite a desperate need to beat her Democratic opponent in the two states in Tuesday's primaries, Senator Hillary Clinton's camp doesn't seem to be running Web display ads at all.

Media coverage of 2008 presidential campaigning on the Web has been dominated by talk of social networking, blogs, viral video, and other tough-to-track social media phenomena. No campaign staffer worth his salt would deny the potential impact of an Obama supporter posting a link on her MySpace page to the candidate's site. However, the fact is many of the campaigns have used a far more measurable online campaign method: paid display advertising.

Republican Presidential candidate Mitt Romney was back online in a big way last month, aiming to rally supporters and establish a platform of popular conservative issues like government spending and border security. Romney For President ran over 22 million Web ad impressions in September, according to Nielsen/NetRatings AdRelevance. Meanwhile, perennial online advertiser John McCain 2008 reduced its display ad impressions from 191,000 in August to 25,000 impressions in September.

Neilsen has published some fascinating details on how the presidential candidates are spending their media money and what kind of results they're getting for it. MarketingCharts.com has the numbers; here are some highlights:

John Edwards is taking a big first step for mobile advocacy in '08. In a fundraising email yesterday, Edwards asked supporters to contribute money for a full-page ad to run in The Washington Post that shows the 100,000 names signed on to his petition to end the war in Iraq. You can see the ad here.

A full-page advocacy advertisement is not notable by itself, but take a look at the bottom of the page. In addition to directing people to his web petition, the ad gives the option to show your support by texting "Iraq" to 30644, an SMS short code set up by the Edwards campaign.

The Web on the Candidates

Mitt Romney's appearance in YouTube's Spotlight series has been a a big success, writes the TubeMogul blog. His video views have skyrocketed -- "looking at Mitt’s own YouTube views, it almost looks as if he wasn’t online prior to that video – he went from about 3K views a day to 125K on 4/13!" It's interesting that although Romney's videos have peaked at around 125,000 views, they've since fallen to around 40,000 views a day. "From a little analysis you can find that the majority of Romney’s views were for his one video asking for information, not on videos where planks of his platform are espoused. Will Mitt be able to continue the debate on YouTube with the energy he just started?," TubeMogul writes.

At the National Association of Broadcasters/Radio Television News Directors Association in Las Vegas, Jeff Jarvis heard some interesting news about the state of political advertising on television and online. At a panel on which he appeared, a "political media man" said that while he was used to spending 80 percent of his money on TV, he was now spending 60 percent online. And at the same session, Joe Trippi "said that the Hillary Clinton 1984 commercial was viewed 4 million times on YouTube but probably 50-60 million times with broadcast included. A message that clicks can be made for nothing and seen by the nation."