Updated

Floridians, tourists and thousands of visitors for the Republican National Convention were warned Saturday to prepare for Tropical Storm Isaac, which is expected to strengthen to a hurricane by the time it reaches the Florida Keys.

While there were few signs of the approaching storm in Tampa, convention officials called off most events until the storm passes. They planned to convene briefly as planned on Monday, then postpone most of the schedule until Tuesday afternoon.

Streets were already shut down around the Tampa Bay Times Forum, where former Massachusetts Gov. Mitt Romney is expected to accept his party's presidential nomination Thursday night. Law enforcement milled about downtown, and some protests already were under way. One group protesting homelessness and the housing crisis "took over" a foreclosed home by cleaning the yard and planned to help a homeless couple move in.

Florida Gov. Rick Scott, a Republican, declared a state of emergency and canceled his plans to attend convention events on Sunday and Monday.

A hurricane warning had been issued for the Florida Keys, and officials warned tourists to leave. Forecast models show Isaac likely won't hit Tampa head-on, but it could lash the city with rain and strong winds just as the convention ramps up. A tropical storm warning was extended up Florida's Gulf coast north of Tampa Bay.

"I told some of my Democratic friends, 'We are the storm, baby, we are the thunder,'" said Steve Linder, whose business is planning all events for the Michigan delegation. Linder added, smiling, "and it ain't gonna stop until November."

Dianne Joachim of New Richmond, Wis., was in town for her first convention and vowed not to let Isaac ruin it.

"I just figure God's got this," she said as she arrived at her downtown hotel.

Scott said during a media briefing that delegates were being told how to stay safe during a storm, and officials were ready for storm surge, bridge closures and other problems that could arise during the convention. He also said he was in close communication with local, state and federal agencies, as well as convention officials.

"We are a hospitality state. We know how to take care of people and we want to ensure their safety," the governor said.

Isaac was blamed for at least three deaths after dousing flood-prone Haiti and was expected to scrape eastern Cuba on Saturday. It was forecast to hit the Keys late Sunday or early Monday, and it then could bring stormy conditions to Florida's west coast before moving to the Panhandle.

Isaac was expected to pass over the Keys as a hurricane late Sunday or early Monday. A steady stream of cars moved north along the Overseas Highway on Saturday, but officials said there were no major problems as some evacuated. At spots of higher ground along the highway, the only road connecting the Keys, dozens of people parked their cars to escape flooding.

At The Turtle Hospital in Marathon, workers were moving recovering turtles from outdoor tanks inside, and hospital founder Richie Moretti said warnings were being taken seriously. He noted Hurricane Wilma in 2005 was initially expected to hit as a Category 1 storm, too.

"It took out the motel, the hospital, the docks, and all the boats. So, I don't take anything for granted. If there's a storm coming, I don't care what number they give it. We're going to batten down and be ready," he said.

Volunteers carried in supplies at shelters throughout the Keys. On Duval Street, the famed tourist strip in Key West, many shops were boarded up. Bands of light rain moved through and passersby crowded under umbrellas and wore ponchos and slickers.

"The weather sucks, but on Tuesday it'll be nice," said an optimistic Kelly Calhoun, a 30-year-old speech therapist at the start of a weeklong vacation to Key West with family. "We got all the essentials: booze and food."

Yet the storm was days away from the Florida Panhandle. It was sunny and breezy on the beach Saturday in Pensacola, with people out strolling and playing in the sand. Condo associations told people to move furniture inside, but full-scale preparations hadn't yet begun. Waves weren't yet big enough for surfers.

When the storm hits, strong winds will be "enough to knock you over" and produce severe thunderstorms, National Hurricane Center spokesman Dennis Feltgen said.

Storm surge and tornadoes also are possible when Isaac hits, and winds could topple power lines and lead to lengthy power outages, Feltgen said. The Panhandle already has had a wet summer, so potential flooding was especially possible there.

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Associated Press Writers Suzette Laboy in Miami, Tony Winton in Marathon, Matt Sedensky in Key West and Gary Fineout in Tallahassee contributed to this report.