Romney formally chosen as GOP nominee, convention moves into full swing

Mitt Romney was formally nominated Tuesday as the Republicans' presidential candidate, hitting the magic number of delegates late in the afternoon -- capping an eight-year quest for his party's nomination.

Shortly before 6 p.m., Romney notched the 1,144 delegates needed to claim the party nomination going into November. The New Jersey delegation, whose governor is giving the keynote, delivered the final delegates that put him over the top.

The proceedings, as per tradition, were part pep rally for the individual state delegations that one-by-one took the stage and jazzed up the crowd before announcing their delegate totals. But they also concluded what for Romney has been a protracted and hard-fought battle for the nomination -- he is here in Tampa only after warding off a rotating field of feisty primary challengers ranging from Rick Perry to Newt Gingrich to Rick Santorum to Herman Cain.

The nomination sets into motion a convention that until a few hours ago was fairly lifeless. Tropical-storm-turned-hurricane Isaac delayed the convention start by a day and continued to overshadow the event. But the atmosphere at the Tampa Bay Times Forum late Tuesday was ebullient. Concessions were flowing in the halls of the arena, and delegates -- some in state-specific costume -- had been streaming in all day in advance of the nomination and later a slew of major speeches.

Romney and his family, as well as running mate Paul Ryan and his family, touched down in Tampa earlier in the day.

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Romney's wife Ann, upon landing in Tampa, immediately went to the convention site for a walk-through ahead of her speech Tuesday night. She did a quick sound-check, reading the opening of the Gettysburg Address from a teleprompter placed at the back of the room.

On the flight to Tampa, she described her speech as "heartfelt."

The former first lady of Massachusetts is one of several big speakers on deck whose task is to rally the party around Mitt Romney.

With Mrs. Romney poised to tell the American public a bit about her husband's personal side -- and perhaps rebut the Democratic narrative that his candidacy is a threat to women -- New Jersey Gov. Chris Christie is in town preparing for his keynote.

Speaking to the Michigan delegation Tuesday morning, Christie joked that his staff had done "a fabulous job of lowering expectations."

Far from it, the anticipation has been building around his speech, with the party relying on Christie to light a fire under delegates and viewers -- and send everyone home eager to hear the rest of the Republican 2012 story from Ryan tomorrow and Romney himself on closing night.

The entire affair has competition, though, not just from now-Hurricane Isaac, but President Obama.

The president was beginning a three-state counter-programming tour Tuesday with two visits in Ames, Iowa, and Fort Collins, Colo.

Though planned visits by Vice President Biden to Florida this week were canceled due to the storm, Obama is charging ahead with rallies aimed at depriving the Republicans of coverage all to themselves.

Polls show Romney and Obama running about even, but each man holds significant leads with voters in important subtexts that could sway the roughly 10 percent of Americans who say they haven't settled yet on one man or the other.

Obama holds a big lead as the candidate who best relates to the needs of poor and middle-class Americans. That advantage could come into sharper focus as Isaac moves slowly toward the U.S. Gulf Coast after forcing Monday's convention opening to be delayed.

The storm was expected to come ashore late Tuesday or Wednesday somewhere near New Orleans. That resurrected the ghost of Hurricane Katrina, which devastated the city and killed 1,800 people exactly seven years ago.

Trying to balance leadership with campaigning, Obama delivered a brief update on Isaac from the White House before leaving. "Now is not the time to tempt fate," he said. "You need to take this seriously."

Partisanship had not subsided with Isaac's gathering strength. Republicans were determined to play to Romney's strengths this week. He is more highly regarded as the candidate who can restore the economy, the top issue for voters.

Ultimately, it will be up to Romney himself "to let the American people see who he is," said Christie.

Meanwhile, Republican leaders will try to convince Americans that Obama is a failed president, unable to keep his promise to restore economic vitality and reduce stubbornly high unemployment -- still at 8.3 percent three years after the Great Recession.

The Associated Press contributed to this report.