Republicans aren't the only ones determined to come to Tampa, even as Tropical Storm Isaac heads toward Florida. Protesters are coming, too.

Demonstrators representing various causes are beginning to arrive in this Gulf Coast city, just days before the convention that will nominate Mitt Romney for president.

Officials say 15,000 people could show up to demonstrate during the event. It's unclear whether those numbers will diminish if heavy rain and winds blow into the area.

Some protest organizers say they won't be deterred by the rains. Labor organizations, doctors and Planned Parenthood are among the groups scheduled to march and hold demonstrations in downtown Tampa.

On Monday, the first day of the convention, a large demonstration organized by the Coalition to March on the RNC is scheduled for 11 a.m. in downtown. More than 5,000 people are expected to attend that rally.