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Republican Party officials are moving ahead with their national convention plans as a potentially hurricane-force storm approaches, saying they're in close contact with the National Weather Service but anticipate they'll "be fine."

GOP leaders sought Thursday to ease concerns about the possibility that a havoc-wreaking storm could spoil plans to host the four-day convention. which starts Monday in Tampa.

William Harris, CEO of the Republican National Convention, said in a brief statement that "we continue to move forward with our planning and look forward to a successful convention."

Republican National Committee spokesman Sean Spicer said the plans are open to change, but "right now everything is focused on putting on four days of talking about Mitt Romney and Paul Ryan and why Barack Obama has taken this country in the wrong direction."

"It looks like we should be fine," Spicer told Fox News. "If it takes a turn ... we'll make those adjustments."

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    The updates came after Tampa Mayor Bob Buckhorn said Wednesday he's prepared to order an evacuation if necessary.

    Neither Tampa officials nor RNC organizers, though, know whether the storm will be severe or direct enough to warrant such a measure.

    U.S. forecasters said Tropical Storm Isaac will likely turn into a Category 1 hurricane by Friday as it nears the Dominican Republic and Haiti. It was expected to weaken a little while heading over the two-nation island and the eastern two-thirds of Cuba.

    The storm was projected to head toward Florida as a hurricane by Monday, but the U.S. National Hurricane Center in Miami said some forecast models show it could go further west into the Gulf of Mexico, so "significant uncertainty remains about the threat Isaac poses to Florida."

    Harris said Republican officials will "work closely" with the emergency officials and the National Weather Service to monitor the storm and figure out what the impact might be on the Tampa area.

    Harris said Florida officials have assured convention planners they have enough resources in place to respond to the storm should it make landfall. He said the primary concern is for those in the storm's path.

    Isaac was centered 165 miles south of Puerto Rico early Thursday afternoon, with maximum sustained winds of 40 mph. It was moving west at 15 mph, according to the Hurricane Center.

    Florida Emergency Management Director Bryan Koon, who has been coordinating security and convention planning with party officials for more than a year, said Wednesday there was no reason out-of-state visitors should cancel their plans.

    "The storm is so far away at this point, the cone of error from this point out is tremendous," said Koon, who has been in constant contact with RNC officials about the storm threat.

    The city's geography has posed logistical challenges from the outset, including how people would get around a downtown that is only about 571 acres -- or less than 1 square-mile -- and is bordered by interstates and rivers, and punctuated with restaurants, cafes and offices. As many as 400 air-conditioned buses are expected to shuttle delegates and other visitors from their hotels on both sides of the bay to the Tampa Bay Times Forum, the downtown hockey arena hosting the festivities.

    Any evacuation orders for the arena, where Romney will give his acceptance speech, would depend on a variety of factors, and would most likely not be made simply because a Category 1 storm, with winds of 74 mph, was approaching, officials said. Some visitors may not even be staying in would-be evacuation zones. Hotels have been booked 20 miles or more from downtown Tampa.

    It's unclear what might happen to convention plans if the opening days are canceled due to severe weather. Asked whether the RNC would be able to book all the same venues at a later date, Buckhorn said: "I guess we'll have to cross that bridge when we get to it" -- if they get to it.

    The Associated Press contributed to this report.