We’ve been shielded from those exasperating negative political ads thus far, but rumor has it Twitter will be displaying political ads as early as this week.

Be on the look out for campaign slogans, political endorsements, and of course, underhanded mud-slinging in your Twitter feed over the next few weeks. According to Politico, political ads will start running on Twitter this week.

Adam Bain, Twitter’s president of global revenue, explained why the company is diving into the political arena:

“We’ve had five years to watch and observe how people are using the platform organically and we know politicians are active on the platform, and we know that consumers enjoy the messages from those politicians. We’re excited about the election cycle, and we think that ads both in the timeline and in search are a huge opportunity.”

And Twitter is going big: among the first political clients are five 2012 presidential candidates.

Bain wouldn’t give any specifics, but Politico’s sources say that Mitt Romney’s campaign and the Democratic Senatorial Campaign Committee will be among the first clients.

Update: Twitter has confirmed that they are accepting political ads starting today. The dedicated political sales team will be run by new hire Peter Greenberger.

Political ads will be less obtrusive than commercial ads, at least to begin with. They’ll use the traditional Promoted Tweet, which will appear (along with a logo and disclaimer) at the top of search results whenever a user searches for a particular term on Twitter, Promoted Trends, and Promoted Accounts.

Sponsored political tweets will be distinguished from commercial tweets by a small purple checkmark. And disclosures including “Paid for by” will be visible when the user hovers over the political tweet.

Are you ready for political ads on Twitter? Let us know in the comments below.