TAMPA, Fla. — Republicans on Tuesday nominated Mitt Romney and Paul Ryan as their 2012 White House ticket.

Romney, 65, is seeking to unseat President Barack Obama in a race that polls say has been too close to call for months.

Romney’s triumph Tuesday caps a five-year quest for the nomination that has rarely been smooth. Even Tuesday, the former Massachusetts governor, once viewed as a moderate eager to find common ground with Democrats, faced questions from the rank and file about his loyalty to the conservative views he’s touted during his White House bid.

Having Ryan, 42, the Wisconsin congressman and House Budget Committee chairman, has helped immensely, as Romney and Ryan easily won majorities of the 2,286 delegates.

Former New Hampshire Gov. John Sununu, who served as President George H.W. Bush’s chief of staff, formally nominated Romney. His state, which his son once represented in the U.S. Senate, is considered a swing state in November.

“We’re saddled with a failed presidency with an incumbent President who has not led,” Sununu told a crowd that seemed more absorbed in conversation. He got little applause.

Sununu would pause, waiting for cheers that rarely came, with lines like, “There are many reasons America needs Mitt Romney at the helm. Barack Obama can’t figure out what makes the private sector work.”

The roll call of states was followed by a night of speeches aimed at sending a message to voters that Republicans know how to fix the economy and Obama doesn’t.

Romney’s wife, Ann, talked about her husband’s warmer side.

“I know this good and decent man for what he is — warm and loving and patient. He has tried to live his life with a set of values centered on family, faith, and love of one’s fellow man. From the time we were first married, I’ve seen him spend countless hours helping others.”

She also was vehement that her husband knows how to succeed. “No one will move heaven and earth like Mitt Romney to make this country a better place to live,” Ann Romney said. “It’s true that Mitt has been successful at each new challenge he has taken on. It amazes me to see his history of success actually being attacked.”

She added, “And let’s be honest. If the last four years had been more successful, do we really think there would be this attack on Mitt Romney’s success? Of course not.”

When she was done, the loudspeakers boomed the Temptations’ “My Girl,” and Mitt Romney walked out from the wings, hugged and kissed his wife and waved to the crowd.

She was followed by keynote speaker Chris Christie, the governor of New Jersey, who spoke of his family’s immigrant roots and his vision for this country.

“We are the great-grandchildren of men and women who broke their backs in the name of American ingenuity; the grandchildren of the Greatest Generation; the sons and daughters of immigrants; the brothers and sisters of everyday heroes,” he said.

The Democrats’ plan, Christie charged, is to “whistle a happy tune while driving us off the fiscal cliff, as long as they are behind the wheel of power when they fall.”