High winds and lashing rains are wreaking havoc on the schedule of this week's U.S. Republican national convention in Tampa, Florida.

Republicans are expected to formally nominate Mitt Romney and his vice presidential running mate, Paul Ryan, as their candidates to face Democratic President Barack Obama and Vice President Joe Biden in the November election. But Tropical Storm Isaac has forced the party to delay the start of convention activities.

The storm started whipping southern Florida Sunday with winds and rain after causing damage and deaths in the Caribbean.

Republican officials say safety concerns prompted them to postpone opening the convention until Tuesday.

Romney is still scheduled to deliver his acceptance speech on Thursday.

The storm also has impacted protesters who have been gathering in downtown Tampa.

Anti-Romney protester John Penley says turnout has been less than expected.

“I think part of what's going on is that people want to see what's going on with the weather; we expect that majority of people to get here today, and people are waiting to see because why come here and then just have to turn around and leave because of a hurricane or really, really strong winds are going to hit the city.”

Some Republican strategists are growing concerned that should Tropical Storm Isaac turn into a hurricane, it could overshadow the convention and Mitt Romney's acceptance speech.

During an interview with Fox News Sunday, Romney said he hopes the speech conveys his belief that the nation is “unique and exceptional,” and continues to have the tools needed “to lead the world in prosperity and in peace.”