Twitter becomes a key real-time tool for campaigns Within moments after Obama finished his remarks, Twitter users had written more than 20,000 posts containing "#dontdoublemyrate" - enough for Twitter to declare it a Top 10 worldwide "trending topic." The six-year-old microblogging site came into its own this presidential cycle, but the past few weeks have demonstrated how clearly it has become the tool of choice for getting something into the political bloodstream, from manufacturing a battle over who can be called a working mom to building a movement around a piece of legislation. And the fact that the president is now incorporating hashtags into his speeches shows how Twitter is redefining the means by which politicians shape, distribute and refine their messages. Campaigning in 140 characters or less provides almost instant feedback, which campaigns use to figure out what is working and what isn't, even before it hits the blogs, much less the traditional media outlets. But as both sides are learning, once they enter the Twitterverse, the digital currents can sweep in many directions. Conservatives seized upon Obama's #dontdoublemyrate hashtag to complain about gas prices and unemployment. And the GOP-leaning U.S. Chamber of Commerce quickly bought space on Twitter to assure that everyone searching for the hashtag saw its tweets at the top of their computer screens. Within 45 minutes of Obama's speech, Speaker John Boehner (R-Ohio) had picked up the hashtag on his Twitter feed - to argue that Democrats, not Republicans, were responsible for the fact that student loan rates are set to double. "Twitter has become the ultimate real-time engagement tool for our campaign," said Zac Moffatt, digital director of GOP nominee Mitt Romney, whose operation has grown noticeably more aggressive in its use of the social media service. In the past, for instance, the campaign might have sent out a mass e-mail to protest if a Democratic cable television pundit accused the candidate's wife of never working a day in her life. And quite likely, it would have sunk without a ripple. But when that happened at 8:43 p.m. on April 11, Ann Romney issued her first tweet: "I made a choice to stay home and raise five boys. And it caused a sensation that threw the Democrats on the defensive on women's issues. Where almost no one on Twitter had been mentioning Ann Romney or the strategist Hilary Rosen's name when Rosen made her comment on CNN, the number quickly jumped to more than 150 tweets per minute. And by noon the next day, more than 2,800 Twitter users had sent Ann Romney's tweet on to their tens of thousands of followers. Twitter is dwarfed in size by Facebook, with 24 million active U.S. users at the end of last year, compared with nearly 133 million for Facebook, according to an estimate by the research firm eMarketer. But it is growing more than twice as fast, at 31.9 percent last year.