Republicans formally nominated Mitt Romney to challenge President Barack Obama for the White House, kicking off their storm-delayed convention with a barrage of sharp attacks on Obama's economic leadership.
The nomination sets up a two-month dash to the Nov. 6 election, with polls showing Romney running even or slightly behind the Democratic president.
Finally opening the festivities after a storm threat delayed the convention by a day, Republicans on Tuesday evening condemned Obama's economic record and reminded voters of the country's stubbornly high unemployment rate and ballooning budget deficit.
Reince Priebus, chairman of the Republican National Committee, warned that re-electing Obama would mean four more years of failure.
We have a message for America: Elect Mitt Romney and Paul Ryan and they'll get America working again, he said to loud cheers. We must send America's comeback team to Washington.
The first 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 make an aggressive argument to voters to replace Obama while being careful to avoid the appearance of unseemly celebration as New Orleans and swathes of the Gulf Coast were under threat from Hurricane Isaac.
Romney is struggling to overcome a likeability gap with the president and refute Democrats' efforts to paint him as a job-killing former private equity executive who is out of touch with middle America.