Mitt Romney vowed to rescue the US economy and create jobs Thursday as he accepted the Republican presidential nomination at the climax of a convention that sought to humanize the candidate.

"What is needed in our country today is not complicated or profound. It doesn't take a special government commission to tell us what America needs," Romney said in his prime-time pitch. "What America needs is jobs. Lots of jobs."

The former Massachusetts governor told Americans that Barack Obama had singularly failed to deliver the "hope and change" he had promised and that the country must elect Romney to save an economy crippled by wrong-headed policies.

"Our problem is not that he is a bad person, our problem is that he is a bad president," Florida Senator Marco Rubio agreed as part of a barnstorming introduction to Romney that did the rising star's lofty ambitions no harm at all.

Romney's elevation to official challenger to Obama in the November election comes more than five long years after he launched his first White House bid and with the current race neck-and neck and dependent on a handful of key states.

The convention injects momentum into the Republican campaign as Romney slingshots out of Tampa on a 10-week dash across battleground states like Florida, Ohio, Virginia and Colorado -- any of which could decide the race.

After trailing for months, the multimillionaire former venture capitalist has recently drawn even in national polls with Obama, an incumbent saddled with a sluggish US economy and stubbornly high unemployment.

Romney has touted his business acumen, arguing that he has the skills necessary to steer America back to prosperity, but he trails Obama badly in terms of likability and can come across as stiff, awkward and out-of-touch.

He sought to blunt that advantage from the moment he entered the convention hall, surprising delegates by striding in on a red carpet and hugging and kissing dozens of supporters before taking his place on stage, his eyes wet with emotion.

"Tonight I am asking you to join me to walk together to a better future," he said, adding that the running mate he chose, Paul Ryan, is "a man with a big heart from a small town (who) represents the best of America."

The job of softening Romney's edges has largely fallen to his wife Ann, who brought down the house Tuesday with a rousing speech about their high school romance, their all-American family and his devotion to public service.

During Thursday's climax to three nights of raucous political theater, a succession of speeches and appearances completed a carefully choreographed attempt to reintroduce Romney as a more touchy-feely character.

His son Craig was followed by members of Romney's Mormon church, a cohort of Olympians, and even a surprise cameo from legendary Hollywood star Clint Eastwood, as the Republicans launched a coordinated charm offensive.

Romney himself did not dwell on his faith, a form of Christianity that many still distrust, but his speech did contain personal anecdotes intended to help him connect better with middle-class Americans.

"My mom and dad gave their kids the greatest gift of all -- the gift of unconditional love. They cared deeply about who we would be, and much less about what we would do," he said.

Wrapped inside his family message was also a targeted pitch at the women voters who could prove decisive on election day but risk being alienated by Republican positions on social issues like abortion.

"My mom and dad were true partners, a life lesson that shaped me by everyday example," he said.

"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?'"

But the overriding narrative of Romney's speech was that Obama had had his chance and failed, and it was time to elect someone who could turn things around.

"Hope and change had a powerful appeal. But tonight I'd ask a simple question: If you felt that excitement when you voted for Barack Obama, shouldn't you feel that way now that he's President Obama?" Romney asked.

"Today the time has come for us to put the disappointments of the last four years behind us," he added.

"Now is the time to restore the promise of America."

The Obama campaign was left unimpressed.

"Much like the entire Republican convention, Mitt Romney's speech tonight offered many personal attacks and gauzy platitudes, but no tangible ideas to move the country forward," said Obama campaign manager Jim Messina.

"What he didn't share were his actual proposals, which would take our country backwards."

"In an almost 45-minute speech, Mitt Romney didn't find a moment to mention Afghanistan. With no new plans and evasion about his real plans, Mitt Romney leaves this convention no stronger than he came."