How the #IAcaucus played out on Twitter The @MentionMachine launched Tuesday in time to illustrate the biggest story of the Iowa caucuses - Rick Santorum's burgeoning momentum and near-win. Chris Cillizza showed in the Fix that Santorum's buzz was evident from the volume of tweets about about him (64,306) versus those about frontrunner Mitt Romney (44,193) over the 24 hours surrounding the caucuses. That spike in Twitter volume about Santorum continued Wednesday morning. He passed President Obama for the 2012 candidate with the second-most Twitter mentions in the past week, behind perpetual Twitter traffic frontrunner Ron Paul . Leaderboard on Jan. 4, 2012. (@MentionMachine) There were other big moments for the social Web over the hours between 8 p.m. ET, when the caucuses began and the early morning hour when they were called for Romney. Mentions of all the candidates ticked up during the caucuses, but Michele Bachmann didn't receive nearly the attention her rivals did during them. She peaked at 3,344 mentions in the 10-11 p.m. EST hour. The announcement early Wednesday that she would hold a news conference and her subsequent withdrawal from the race earned her more mentions than anything else that happened over the week leading up to the caucuses. (@MentionMachine) Rick Perry's @MentionMachine track was similar, as the bulk of tweets about him came through between 11 p.m. and midnight, when he announced he was returning to Texas to "reassess" his campaign. Perry's mentions spiked again when he tweeted "On to South Carolina" on Wednesday morning, despite speculation his earlier remarks meant he would drop out of the race. Jon Huntsman didn't participate in the Iowa caucuses, but his @MentionMachine count spiked to 2,600 mentions in the 8 p.m. hour Tuesday when the Paul campaign sent this tweet: The Paul campaign has since deleted the tweet, but versions of Paul's tweet are still the top tweet about Huntsman for the entire week on @MentionMachine. Paul wasn't apologetic when CNN's Soledad O'Brien questioned him about it, our colleague Erik Wemple reported. Twitter volume was still strong for the two frontrunners late into the night and early in the morning, but attention on them to a back seat to "Edith and Carolyn," two Iowa Republican women whose 1 a.m. phone exchange with CNN After Dark anchors became a trending topic on Twitter. Not familiar with the @MentionMachine yet? Watch this video to see how it works. Follow @MentionMachine on Twitter