NEW YORK -- Twitter is abuzz with presidential candidates this year, though not all in the Twittersphere are equal. Rick Santorum tweets a lot more than Rick Perry, Herman Cain is the Republican most likely to be retweeted, and their Twitter followers are dwarfed by President Barack Obama's. That's according to an Associated Press analysis of the presidential candidates' use of Twitter that found widely different levels of engagement, despite the site's emergence as a go-to hub for political communication. The AP analyzed each candidate's Twitter stream beginning the day he or she joined the presidential contest through Oct. 24. The data highlights every message posted by candidates, as well as how many times their messages were "retweeted," or reposted, by other users on the site. No one believes the campaign will be won or lost on Twitter. But with a well-timed 140 character blast, candidates can make news, respond to charges or reinforce talking points in a matter of seconds. "And unlike pricey television and Web advertising, tweeting is free. That's one reason some of the financially struggling candidates have relied on Twitter. The AP found the Newt Gingrich campaign, which trails other rivals in fundraising and is more than $1 million in debt, to be one of the most active on Twitter. Gingrich has tweeted more than 470 times as of last Monday. Rick Santorum, the former Pennsylvania senator, had tweeted 326 times to more than 35,000 followers. Perry, the well-funded Texas governor, is at the other end of the Twitter spectrum. His campaign has sent 42 tweets to more than 99,000 followers under his Twitter handle, @GovernorPerry, since he launched his presidential campaign in August. Former Massachusetts Gov. Mitt Romney's campaign has tweeted 233 times under the Twitter handle @MittRomney to more than 150,000 followers, almost all directly from Twitter's website. The success of a candidate's Twitter strategy can in part be gauged in how often a candidate's message is retweeted by followers to a broader audience. By that measure, the AP analysis found Cain has outpaced his GOP rivals. He has sent 579 messages to about 142,000 followers under @THEHermanCain handle since joining the race. Despite their best efforts, none of the Republicans are in the same league with the president when it comes to the successful use of Twitter. Obama, whose campaign revolutionized the use of the Internet as a fundraising and organizational tool in his 2008 campaign, has 10.8 million Twitter followers. His campaign, under the handle @BarackObama, has tweeted 731 times since launching his re-election bid. Most of his tweets are sent by staff, but Obama has personally tweeted a handful of times. Tweets directly from the president are signed -bo. Obama's digital advisers acknowledge the campaign had a huge head start online against the Republican field. But they also maintain the success of their Twitter strategy, particularly measured by their retweets, comes from using Twitter to ask supporters to take a specific action - attending an event, watching a speech, sharing their story about how his jobs plan might help them. The Republicans haven't learned yet how to make best use of the platform, Obama advisers say. "Fundamentally, you are trying to shape a relationship with voters. Go volunteer, donate, go vote. It's not a novelty for us," Obama campaign digital director Teddy Goff said.