Romney began the convention less popular than any major candidate in recent political history, as measured by polls back to 1984. A new Washington Post-ABC News poll finds his unfavorability at its highest point, with 51 percent of Americans expressing negative views of the nominee.
Republicans see the convention, with an expected television audience of tens of millions, as one of the biggest opportunities between now and November to reset the campaign dynamic. They hope it will act as a palate-cleanser after a bitter summer of attacks and counterattacks, and give them an opportunity to provide voters a fuller, more flattering impression of their nominee and his running mate.
"For the first time, many Americans will see Mitt Romney talking about himself and seeing a lot of other people talking about him, including me," Portman said. "I think this will be the start of not reintroducing, but introducing the real Mitt Romney to folks who have only seen at this point an amazing array of negative campaign ads."
The convention was not a tableau of perfect harmony. There remained an unmended rift between Romney's supporters and the minority of delegates supporting libertarian Rep. Ron Paul, R-Texas.
Paul arrived on the convention floor with a great stir. His supporters and Romney's shouted at each other. "Let him speak!" Paul's backers yelled, referring to the decision to keep him away from the convention podium. "Romney!" others chanted back.
Paul's supporters are annoyed with rule changes, passed Tuesday, that might limit their power in the next election cycle. The changes would weaken state-level party conventions, small gatherings where Paul supporters have had more success than in popular votes.
"They're trying to stage a coup and make the grass roots completely irrelevant for the future," said alternate delegate and Paul supporter Jeremy Blosser, 36, of Fort Worth, wearing his delegation's white cowboy hat as he waited for the opening gavel early Tuesday afternoon.
Tuesday night, delegates in the Tampa Bay Times Forum convention hall waved signs saying "We built it" - mocking an Obama statement that businesses owners are not solely responsible for their successes.
"If you've got a business - you didn't build that," the president said at a rally in Virginia on July 13. "Somebody else made that happen."
Democrats point out that, in context, Obama's comments referred to government-built infrastructure such as roads and bridges, as well as research that went into creating the Internet.
Still, the comment has become a favorite Republican theme, one that echoed many times in the speeches Tuesday.
"You did make that happen," Virginia Gov. Robert F. McDonnell declared to cheers from the delegates. "Big government didn't build America. You built America."