Romney pledged policies that would create 12 million jobs, though he offered few details.
"America has been patient. Americans have supported this president in good faith. But today, the time has come to turn the page," he said. "Today the time has come for us to put the disappointments of the last four years behind us. To put aside the divisiveness and the recriminations. To forget about what might have been and to look ahead to what can be."
For the most part, he avoided the acerbic tone of the campaign, though he did, at one point, mock a moment of grandiosity from Obama's 2008 campaign.
"President Obama promised to begin to slow the rise of the oceans and heal the planet," he said. "My promise is to help you and your family."
Romney's nationally televised speech to tens of millions was his largest audience to date, an unfettered chance to state his case - that he has the competence to confront the problems of the economy based on his business background as head of a private-equity firm.
His triumph came after years of trying to convince Republicans that he was conservative enough to represent them. He has been running for president since the end of his one term as Massachusetts governor in 2007.
Actor Clint Eastwood provided a surprise and somewhat discursive warm-up act for Romney, talking to an empty chair meant to represent Obama; egged on by some in the hall to use a catchphrase from his Dirty Harry films, Eastwood ended by saying, "Go ahead." The audience roared back, "Make my day."
Earlier, friends took the podium to attest to Romney's compassion for people as a lay Mormon pastor, executives of successful companies financed by his Bain Capital firm praised his talent, and Olympic athletes attested to his turnaround of the troubled 2002 Winter Olympics in Salt Lake City.
To get to Thursday's podium moment, Romney survived one of the wildest presidential nominating contests in decades; any number of things could have stopped him. For instance, Romney barely fended off a surging Rick Santorum, 41 percent to 38 percent, in Michigan's February primary. If he had lost his native state, would he have been standing on the Tampa stage Thursday?
Perhaps, but that is just idle musing now because Romney persevered. He ground it out day after day, sticking to his plan, until all his opponents were dust in the wind.
Given that lunch-pail style, it seems more ironic that one major rap against Romney as a candidate is his difficulty relating to ordinary voters.
Romney, a successful private-equity investor, founded Bain Capital, which bought and sold companies and funded start-ups like Staples and Best Buy. In the Democratic telling, that part of his resume is a negative; they highlight times Bain profited while saddling companies with debt and taking them into bankruptcy, costing jobs, to portray Romney as a heartless.
"He's not a back-slapper . . . He's not a gregarious guy," senior adviser Ron Kaufman said of Romney earlier in the convention week. "He's not a good politician in the traditional sense." Kaufman argued that likability is overrated - voters, he said, do not want a beer buddy but an executive who knows how to confront the country's economic problems. Romney has a record of inspiring his employees, digesting opposing advice, and, most important, the "desire to make a decision," Kaufman said.
Yet there is no doubt that the presidential race is intensely competitive. Romney and Obama are running within a few percentage points of each other in national and battleground-state polls. Their shares of the vote in opinion surveys have not fluctuated much over the last several months, regardless of developments in the campaign or in the news.
Romney pulled virtually dead even with Obama or slightly ahead in Sunday's Gallup tracking poll of the nation. In 15 of the last 19 elections, the candidate leading Gallup's last survey before the first nominating convention has gone on to win. That is not dispositive, of course, because the environment is so volatile. The Democrats hold their convention in Charlotte next week, potentially shortening the traditional postconvention polling "bump" for Romney, unlike in past cycles when the two party gatherings were separated by a couple of weeks.
In his speech, Romney talked in personal terms about his mother, in step with his campaign's efforts to reach out to women voters in hope of closing the gender gap that has aided the president.
He said the secret to his parents' 64-year marriage was best-known to "the local florist - because every day Dad gave Mom a rose, which he put on her bedside table. That's how she found out what happened on the day my father died - she went looking for him because that morning, there was no rose."
He recalled his mother's brief political career: "When my mom ran for the Senate, my dad was there for her every step of the way. I can still hear her saying in her beautiful voice,'Why should women have any less say than men about the great decisions facing our nation?' "
It was here in Tampa nearly a year ago that Romney was facing his biggest threat - when Texas Gov. Rick Perry, the conservatives' hope, joined the GOP field for a tea party-sponsored debate at the Florida State Fairgrounds, before a rowdy audience. Romney tore his head off. Perry got booed as he was pressed for being insufficiently tough on illegal immigration, and Romney methodically went after Perry's oft-quoted belief that Social Security, which has become a deep part of the American fabric even to conservatives, was a "Ponzi scheme."
Then, in turn, Romney bested other conservative challengers - former House Speaker Newt Gingrich and Santorum. He had won a war of attrition, accumulating delegates while waiting for lesser rivals to blow up, and helping them do it.
Political scientists say Romney is not a transformational nominee, one of those leaders who comes to shape the identity of the party more than the other way around: Ronald Reagan in 1980; Bill Clinton and his centrist "third way" retooling of the Democrats in 1992; George W. Bush in 2000, with "compassionate conservatism." Instead, today's GOP is known more by its firebrands on Capitol Hill.
"Since Romney isn't reshaping the party in the way those figures did, that doesn't give him a lot of room to maneuver," said Dante Scala, a political scientist at the University of New Hampshire. "He's on a short leash."
Even so, Romney chose Thursday night to point straight at the achievements of his Bain years, and used them to point back to his party's critique of the Democrats and Obama: "He had almost no experience in business. Jobs to him are about government."
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Contact Thomas Fitzgerald
at 215-854-2718 or tfitzgerald@phillynews.com, or follow @tomfitzgerald on Twitter. Read his blog, "The Big Tent," at www.philly.com/BigTent.