It was keeping everyone guessing. It could blow up to hurricane strength and steer toward Tampa, or crumble over Cuba, or lightly skirt Florida's west coast - the likeliest situation Thursday - bringing nothing more than pesky rain and a puff of wind.
There is reason for optimism. The last time a major hurricane made a direct hit on Tampa, on central Florida's western side, was when Warren G. Harding was president. (It was 1921, a nonconvention year.)
"If anybody is prognosticating doom and gloom, I think they are premature," said Ken Jones, the chief executive officer and president of the 2012 Tampa Bay Host Committee.
"Right now, everything is full speed ahead," he added.
But if there is one thing that politicians dislike, it is unscripted, unpredictable events. With 50,000 people scheduled to arrive by Monday, and hordes of journalists watching and waiting, Tropical Storm Isaac - even in its weakened state far, far away - is draining valuable time and attention away from the convention itself.
"In politics, you hate things that are not in your control," said John Weaver, who was once one of Sen. John McCain's closest advisers.
Democrats are patting themselves on the back. Howard Dean, who once led the Democratic National Committee, said the party had long ago agreed to stay out of Florida during the summer. Too risky, he said. The last convention held in Florida was in 1972, when both Democrats and Republicans gathered at Miami Beach.
At a time when the Republican Party is eager to focus on jobs, the economy, and Romney's fix-it plans, the storm could prove a scene-stealer, at best.
Hollie Wade, a spokeswoman for the Hillsborough County Office of Emergency Management, said the county had spent considerable time preparing "for every contingency you can imagine."
For now, forecasts show that the storm could become a Category 1 hurricane, the least powerful.
"There's not an anticipation that there will be a cancellation," Gov. Rick Scott, a Republican, said of the convention.
A hurricane could force evacuation of the convention arena and close key bridges, which would pose a logistical problem. Meanwhile, party coordinators are scouting for places to shift outdoor events. Regardless, the word is out that delegates should brace for a soggy kickoff.
"Under the category of lucky guess, we ordered 300 umbrellas two days ago," said Scott Cottington, a partner at Conventions 2012, a conventions services and planning company.
"They are $3 umbrellas," he added, "so I don't know if they will last a week."
There is an upside: "They are red."