Presidential candidate Mitt Romney flew to Tampa on Tuesday to join fellow Republicans seeking to put their shortened convention back on track and prevent his message from being drowned out by a tropical storm bearing down on the US Gulf Coast.Finally getting down to business after Tropical Storm Isaac upended the convention schedule, delegates will formally affirm Romney as the party's nominee in an evening capped by prime-time speeches by his wife, Ann, and New Jersey Governor Chris Christie.Isaac, nearing hurricane force, was forecast to hit in the New Orleans area seven years after it was devastated by Hurricane Katrina - a painful reminder of how the mishandling of the disaster response under President George W. Bush stained the last Republican administration.Tampa was spared the brunt of Isaac's fury. But a destructive landfall in Louisiana in the next day or so threatens to create an uncomfortable split-screen of television images.The convention will culminate with Romney's nationally televised acceptance speech on Thursday, the biggest speaking engagement of his political life as he heads into a 10-week sprint to the Nov. 6 election. He has spent the past few days rehearsing at his New Hampshire vacation home.Running even with Obama or slightly behind him in most polls, Romney needs a bounce in popularity from the gathering, particularly in the 10 or so politically divided "swing states," including Florida itself, likely to decide the election.Obama showed he was staying on top of the storm situation, warning Gulf Coast residents to prepare for possible flooding, before he left Washington for campaign events in Iowa and Colorado later in the day.Republicans will start setting the stage on Tuesday night with a lineup of speakers expected to rip into Obama for his economic policies, widely seen as the president's most vulnerable point, and argue that the former private equity executive could do a better job."As far as getting our message out, I think we're going to be able to get it out very clearly that President Obama has failed," Romney convention organizer Russ Schriefer said.Keeping the heat on Obama for his "you didn't build that" comment, convention planners have set the day's theme as "We Built It," in a bid to highlight what they see as the president's hostility toward small business.Seeking to humanize RomneyAnn Romney's address to the convention represents a prime opportunity to humanize her husband, who is often seen as having trouble connecting with ordinary Americans. Obama's campaign has sought to exploit this by emphasizing Romney's vast wealth.In Tampa, part of Republican officials' aim is to present Romney's biography - his years as a private equity executive, Massachusetts governor and leader of the 2002 Salt Lake City Winter Olympics - in a flattering way that contrasts with the waves of attacks on Romney by the president and his allies.Ann Romney, who suffers from multiple sclerosis and survived a bout of breast cancer, is perhaps Mitt Romney's most popular surrogate."Having breast cancer wasn't easy," she told CBS's "This Morning" program in an interview that could help set a more sympathetic tone for the wealthy couple. "I've had several miscarriages actually, but having multiple sclerosis was a very, very hard time in my life.Expectations are highest, however, for the keynote speech by the fiery Christie, which is likely to be heavy on red-meat rhetoric for conservatives. Romney's campaign likes Christie's in-your-face style, which has made him a rising political star. The New Jersey governor was on Romney's vice presidential short list and is seen as a future presidential contender."You start turning it around tonight," Christie told ABC's "Good Morning America" program when asked how to overcome some voters' lack of enthusiasm for Romney. "He's going to have to let the American people see who he is."The man Romney did pick as his running mate, Wisconsin congressman Paul Ryan, tops the bill on Wednesday.Another speaker scheduled for Tuesday, Rick Santorum, is a different matter. The former Pennsylvania senator was the last obstacle standing in Romney's path to the nomination and had delivered attack after attack on Romney on the campaign trail.Some Romney advisers disliked the idea of granting Santorum a speaking role, fearing he would go off script. In the end, the campaign agreed in the name of party unity to let him speak.Roll Call of StatesTuesday's agenda will be dominated by the traditional roll call of state delegations that will make Romney's nomination official and approval of the party's election platform.The platform was shaped heavily by conservative members, reflecting the party's move farther to the right in the past decade, and some positions on social issues go beyond what many rank-and-file Republicans support.The anti-abortion language, which makes no exceptions for rape or incest, was approved by the platform panel amid unflattering headlines caused by US Representative Todd Akin, a Senate candidate in Missouri who has said that women's bodies have a way to protect them from impregnation after "legitimate rape."But uppermost in convention planners' minds was Isaac -- and the question of whether it would rob some of Romney's media attention. The storm forced convention organizers to compress the event into three days instead of four.Isaac was expected to make landfall in Louisiana on Tuesday night or early Wednesday, the seventh anniversary of Katrina. The Republicans' convention was also disrupted in 2008 when they chose to delay its start in St. Paul, Minnesota, as Hurricane Gustav hit the Louisiana coast.Republicans then were still reeling from criticism of Bush's handling of Katrina, which killed more than 1,800 people and caused billions of dollars of damage along the coast.Romney, who had originally planned to arrive in Tampa on Thursday to accept his party's nomination, decided to make an earlier appearance on Tuesday to be on hand for his wife's turn at the podium, a campaign official said.Republicans seeking to salvage the convention faced a stiff challenge: help Romney make an aggressive, memorable argument to voters to replace Democratic President Barack Obama while being careful to show sensitivity to those at risk from the storm.Delegates gathering for the typically festive and partisan event were also under pressure to avoid the appearance of unseemly celebration while the Gulf Coast was under threat.