Romney watched on television with his wife, Ann, at a hotel suite across the street from the hall as the convention sealed his victories from the hard-fought primaries and caucuses of last winter.
"I read somewhere that Mitt and I have a "storybook marriage," she said in excerpts released in advance of a primetime speech meant to cast her multimillionaire-businessman-turned-politician husband in a soft and likable light. "Well, in the storybooks I read, there were never long, long, rainy winter afternoons in a house with five boys screaming at once."
"A storybook marriage? No, not at all. What Mitt Romney and I have is a real marriage," she said.
Aides said her husband of 43 years would be in the hall when she spoke.
A parade of convention speakers mocked Democratic incumbent Obama mercilessly from a made-for-television podium, as if to make up for lost time at an event postponed once and dogged still by Hurricane Isaac. Delegates held up signs that proclaimed "We built it," a rebuttal to Obama's saying of American entrepreneurs, "You didn't build that."
The Democratic president has "never run a company. He hasn't even run a garage sale or seen the inside of a lemonade stand," declared Reince Priebus, chairman of the Republican Party.
"Mitt Romney will preserve this exceptional American legacy. Barack Obama will destroy it," said Janine Turner, an actress and radio host.
To send Romney and ticketmate Paul Ryan into the fall campaign, delegates approved a conservative platform that calls for tax cuts — not government spending — to stimulate the economy at a time of sluggish growth and 8.3 percent unemployment.
Polls make the race a close one, to be settled in a string of battleground states where neither Romney nor the president holds a secure advantage. More than $500 million has already been spent on television commercials by the two candidates, their parties and allied outside groups, with millions more to come.
Romney's convention victory was more than five years in the making. He was defeated in his first try for the nomination, in 2008, when he was assailed as a false conservative after a term as governor of Massachusetts.
This time, he had the most money, the largest organization and allies with the deepest pockets, all the better to bludgeon Newt Gingrich, Rick Santorum and other rivals in television ads across a string of hard-fought primaries and caucuses. Even so, conservatives were slow to warm to him, and it took longer than many anticipated for him to lock up the nomination.
Even at the convention, a residue of the struggle for the nomination was evident.
Texas Rep. Ron Paul, who never won a primary or caucus, drew 190 delegate votes to 2,061 for Romney. His supporters chanted and booed after the convention adopted rules they opposed, but were powerless to block, to prevent those votes from being officially registered. "Shame on you," some of his supporters shouted from the floor.
Boehner, presiding over the roll call, made no attempt to have Romney's nomination made by acclamation, even though Ryan's was a few moments later.
The night was Romney's for sure, but some of the loudest cheers were accorded Wisconsin Gov. Scott Walker, a hero among Republicans for fending off a labor-backed recall attempt last spring.
Convention planners squeezed two days of speeches and other convention business into one after scrapping Monday's scheduled opener because of fears that Isaac would make a direct hit on the Florida Gulf Coast.
That threat fizzled, but it was instantly replaced by another — that Republicans would wind up holding a political celebration at the same time the storm turned its fury on New Orleans, devastated almost exactly seven years ago by Hurricane Katrina.
Romney's convention planners said they were in frequent contact with weather forecasters, but they declined to discuss what contingency plans, if any, they had to accelerate plans for him to deliver a formal acceptance speech Thursday night.
Ratification of a party platform was prelude to Romney's nomination, a document more conservative on abortion than the candidate.
On economic matters, it backs extension of the tax cuts enacted in 2001 and 2003 and due to expire at year's end, without exception. It also calls for an additional 20 percent reduction in income tax brackets that Romney favors.
In a time of 8.3 percent unemployment and the slowest economic recovery in the post-World War II era, that went to the crux of the campaign for the White House.
By contrast, Obama wants to allow existing tax cuts to expire on upper income taxpayers, and has criticized Romney's overall economic plans as a boon to millionaires that would raise taxes on the middle class.
The GOP platform also pledges that a Republican-controlled Congress will repeal, and Romney will sign, legislation to repeal the health care legislation Obama won from a Democratic-controlled Congress. So, too, for the measure passed to regulate Wall Street in the wake of the 2008 economic collapse.
On abortion, the platform says, "The unborn child has a fundamental individual right to life which cannot be infringed."
Romney opposes abortions, except in cases of rape, incest, or when "the health and life of the mother" are at stake, he said in a convention week interview.
Obama, who accepts renomination at the Democratic National Convention in Charlotte, N.C., next week, campaigned in Iowa Tuesday as he set out on a tour of college campuses in battleground states in hopes of boosting voter registration among college students.
Before departing the White House, he made a point of appearing before reporters to announce the government's latest steps to help those in the way of Isaac. He signed a declaration of emergency for Mississippi and ordered federal aid to supplement state and local storm response efforts in the state.
His surrogates did their best to counter Romney and the Republicans.
Los Angeles Mayor Antonio Villaraigosa, dismissing GOP attempts to woo Hispanic voters, said, "You can't just trot out a brown face or a Spanish surname and expect people are going to vote for your party or your candidate." He added, "This is a party with a platform that calls for the self-deportation of 11 million people."
Hispanics strongly favor Obama, according to public polls, and Romney and his party have been seeking to win a bigger share of their votes by emphasizing proposals to fix the economy rather than ease their positions on immigration.
Associated Press writers Brian Bakst, Thomas Beaumont, Tamara Lush, Brendan Farrington, Julie Mazziotta, Steve Peoples, Kasie Hunt and Philip Elliott in Florida and Steven Ohlemacher, Alicia A. Caldwell and Jennifer Agiesta in Washington contributed to this report.