As it continues to increase its involvement  in the 2012 election, the social networking service Twitter has told  Politico’s Ben Smith that it will begin this week to sell political advertising.
Five presidential campaigns have already signed up to use the new service, Adam Bain, Twitter’s head of global revenue, told Smith. The ads, which will carry a purple check mark, will appear as “promoted tweets,” which appear as a search result, similar to Google ads; “promoted trends” on the “trending topics” list; and “promoted accounts,” suggested to users who might be interested in the candidate based on their account history.
“As with Google ads, rates are determined by advertisers bidding on search terms,” Smith reports.
Twitter CEO Dick Costolo has made multiple trips to Washington, D.C., including one in May , that saw him meeting with senators and representatives to discuss the analytics tool that Twitter provides to advertisers.
The new service comes as presidential candidates are ramping up  their use of Twitter, while Twitter itself is changing the way  that news organizations like Politico cover the campaign. Twitter held its first-ever presidential town hall  in July.