Gingrich had made his mark by stellar debate performances that set him apart from other candidates. It was one of the reasons why he won by an overwhelming margin in South Carolina. But that changed last week as Romney aggressively attacked Gingrich on his past connections to Freddie Mac and his immigration ads.
Gingrich attempted to turn the tables on his rival in subsequent ads attacking his record as Massachusetts governor. In a new robo-call released ahead of the primary, Gingrich charged Romney with taking away money for kosher food for Holocaust survivors in a senior center.
Fifty delegates are at stake in today's primary, an important number for Romney.
"Today, Florida is the most important thing in the world to me," he told ABC News today.
Romney led by double digits over Gingrich in most polls. The most recent poll, conducted by Quinnipiac University, found Romney outshining Gingrich 43 percent to 29 percent, followed by Santorum and Paul tied at 11 percent.
Santorum, whose daughter was hospitalized earlier this week, was absent from Florida, focusing instead of campaigning in Colorado and Nevada, where caucuses will be held Saturday.
Paul plans a Florida election night party today -- but in Nevada.
ABC News' Elizabeth Hartfield contributed to this report.