Love them or hate them, negative ads have become a virtually unavoidable part of campaigning for political office. With $131.1 million in media expenditures as of June 21, 2012 and millions more at stake before November, this year's presidential candidates are making every dollar count in an attempt to create advertising messages with real staying power.

This week, OhMyGov's media monitoring service checked up on the candidates and their videos to see who has the stickiest ads in the race. First, we selected six negative-message advertisements to compare.

Three of the ads we evaluated were designed by Obama/Biden criticizing Mitt Romney for offshore banking, outsourcing jobs to China, and announcing intentions to “get rid of that” in reference to Planned Parenthood.

Another three were created by the Romney campaign attacking President Obama over healthcare reform, unemployment, and dishonest messaging. The ad sets were chosen primarily because they had a comparable number of views in total, based on numbers given on the candidates' Youtube pages.

To see how effective each message was, we evaluated reactions in the Twittersphere, calculating the number of tweets surrounding each one since the beginning of June. 

As the chart illustrates, the video criticizing Romney for being an “outsourcing pioneer” generated the most tweets and retweets. In fact, the phrase was seized and applied not only to the original video but to other reports of his dubious business practices with Bain Capital.

Popular tweets said, “Unlike outsourcing pioneer Mitt Romney, @BarackObama has fought to keep jobs on American soil,” and “Why won't outsourcing pioneer Mitt Romney release his tax returns? It appears that he is hiding something damning.Lies not working.”

The president's supporters appeared responsible for each one, indicating that the negative message was not only received but adopted by likely voters. Frequent news articles referencing outsourcing as it pertains to both the presumptive GOP nominee and American unemployment have also helped make this particular message one with real staying power.

Though the ad peaked on June 18th, Twitter mentions that use the phrase continue to be in the triple digits. At the same time, Romney's most successful anti-Obama ad sought to capitalize on President Obama's controversial statement: “The private sector is doing fine.” However, many Twitter mentions that cite this remark are responses to news articles quoting the president's statement rather than sharing the ad itself.

Regardless, the gaffe did generate a significant level of anger among presidential detractors, and the phrase seems to have some longterm potential for Romney's campaign.

Less successful was the oft-Tweeted ad that uses a clip of Hilary Clinton saying, “Shame on you, Barack Obama,” obtained during the 2008 Democratic primary. While the video did create a flurry of excitement on Twitter, humor appeared to dominate the reactions. Some tweets were clearly sent by Romney supporters, but others noted, “Am I the only one who laughs when Hillary Clinton says 'Shame on you, Barack Obama' in that campaign ad? See, nothing you say ever goes away,” and “So desperate. Really pathetic.”

Although the video certainly did garner attention, it seems unlikely that the message will have any sort of longevity as the campaign progresses. 

Another interesting component of this analysis, is the fact that YouTube views did not translate into social media conversation. That is, what's popular on YouTube was not necessarily popular among Twitter conversations.

As election season approaches, more money will be put into negative advertising as each candidate seeks a gem that will severely tarnish his opponent's reputation. OhMyGov will be watching to see if either one manages to find that holy grail of campaigning on the race to the White House.