Opinion polls show Romney running even with or slightly behind Obama. The convention's opening was pushed back a day by a storm threat, but Republicans wasted no time in condemning Obama's economic record and accusing him of failing to create enough new jobs or rein in the budget deficit.
"We can do better. We can do a lot better. It starts with throwing out the politician who doesn't get it, and electing a new president who does," House of Representatives Speaker John Boehner said. Republicans repeatedly accused Obama of being hostile to small business owners and smothering them with high taxes and excessive regulations. His signature healthcare overhaul, they said, was an example of big government run amok.
"Unlike President Obama, I know that small businesses are the true engine of our economy - not the government - and what businesses need to grow and create jobs is less taxes and regulation, not more," said US Representative Cathy McMorris Rodgers of Washington.
But as Republicans tried to show a united front against Obama, it was clear the bitter party divisions evident in the bruising presidential primary battle have not been resolved. Supporters of libertarian congressman Ron Paul of Texas and other conservative activists briefly disrupted the opening session, booing a decision to unseat Paul delegates from Maine and institute rules changes they believe will weaken their power in the next election cycle.
The rules changes, approved by the convention on a voice vote, will bind delegates to the results of a state-wide vote and reduce the role of smaller state-level conventions where Paul had success. Opponents of the move said Romney's operatives and the party's establishment were trying to freeze them out. Some noted that during the state-by-state roll call of delegates to count votes for the nomination, only Romney's vote totals were announced from the podium.
"We were disenfranchised by our party. We won't participate with this chaos," said Russell Montgomery, 52, of St. George, Maine. "We won't legitimise this fiasco. This is as bad as the other party - the corruption." The opening night will be capped by prime-time speeches by Romney's wife, Ann, and New Jersey Governor Chris Christie. Romney, who had originally planned to stay out of the spotlight until Thursday night when he accepts his party's nomination, made an early appearance in the Florida host city to be on hand for his wife's turn at the podium.
Republicans hope to use the convention to make an aggressive argument for booting Obama from office while presenting a softer side of Romney, who is struggling to overcome a "likability gap" with the president and refute critics who paint him as a job-killing, out-of-touch former private equity executive.
In excerpts of her speech, Ann Romney said her husband has attacked every challenge he has faced - from reviving the struggling Salt Lake City Olympics to helping her battle multiple sclerosis and breast cancer. "At every turn in his life, this man I met at a high school dance has helped lift up others," Romney, 63, will tell the convention.
"This is the man who will wake up every day with the determination to solve the problems that others say can't be solved, to fix what others say is beyond repair," she said. "This is the man who will work harder than anyone so that we can work a little less hard." Republicans hope the convention will not be overshadowed by Hurricane Isaac, which hit the Louisiana coast not far from New Orleans on Tuesday night, just before the seventh anniversary of Hurricane Katrina's deadly strike on the city. They also worry about being seen celebrating Romney's nomination while swathes of the Gulf Coast are under storm threat. While Tampa was spared the brunt of Isaac, a destructive landfall in Louisiana could create uncomfortable split-screen television images of the convention juxtaposed with the hurricane.
The Republican gathering culminates with Romney's nationally televised acceptance speech on Thursday, the biggest speaking engagement of his political life. Obama, campaigning in Iowa and Colorado, dismissed the Republican attacks and told students at Iowa State University in Ames, Iowa, that the agenda his political foes were rolling out in Tampa made for a "pretty entertaining show."