Twitter executives announced the company will start selling political advertisements, seeking for the first time to profit off of the social media tool's role as a forum for political activity and debate.

The move represents a lucrative opportunity for Twitter, with the 2012 elections shaping up to be the most expensive in history -- President Barack Obama has already set a goal of $1 billion in fundraising.

While Twitter declined to name any specific clients, an anonymous source told POLITICO that Mitt Romney's presidential campaign and the Democratic Senatorial Campaign Committee would likely be involved.

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, Adam Bain, Twitter's president of global revenue, told POLITICO. We're excited about the election cycle, and we think that ads both in the timeline and in search are a huge opportunity.

Twitter users got their first glimpse of 2012 election tweets with a message from Mitt Romney warning that We can't afford four more years of failed leadership. The message bore a small purple arrow that marked it as a political advertisement or a promoted tweet.

Advertiser will also have the opportunity to appear atop lists of trending topics and to have campaign accounts suggested to users whose interests seem to be aligned with the campaign.

Twitter's ubiquity some time ago spread to the political world -- all of the current presidential candidates and the majority of lawmakers in Congress have accounts.

It can also get elected officials into trouble. Former New York Rep. Anthony Weiner, a Democrat, was forced to resign after a lewd Twitter message led to revelations of online relationships with women, and Republican presidential hopeful Newt Gingrich, a prolific Twitter user, had to rebuff allegations that most of his 1.3 million followers weren't real people.

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