High winds and lashing rains are wrecking 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. The bad weather forced the cancelation of hundreds of flights at airports in the southern part of Florida, and prompted some precautionary evacuations along low-lying levels in the Gulf of Mexico.

Republican officials say that safety concerns prompted them to postpone until Tuesday many of the speeches and events originally planned for Monday. Other officials say there is a chance the convention will be extended to Friday to accommodate all of the activities.

Romney, who is at his vacation home in New Hampshire, is 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.”

The Republican hopeful also distanced himself from recent comments by Republican Representative Todd Akin who angered many voters last week by suggesting that women's bodies can prevent pregnancy in cases of what he called “legitimate rape.”

Romney said that while governor of Massachusetts, he helped women by implementing universal health care law in the state, an accomplishment he was proud of. He has vowed to repeal Mr. Obama's health care overhaul if elected.

On Sunday, Mr. Obama picked up a political endorsement from former Florida governor — and former Republican — Charlie Crist.

In an opinion piece in the Tampa Bay Times, Crist called the president “the right leader for our times.”

Crist, who is now an independent, was defeated in his bid to join the U.S. Senate in 2010 by Republican Marco Rubio.