Citing a chance of thunderstorms, convention organizers scrapped plans for Obama to speak to an enormous crowd in a 74,000-seat outdoor stadium and decided to shoehorn the event into the convention arena, which accommodates 15,000.
That means no reprise of the massive show of support, excitement and on-scene voter registration from Obama's 2008 acceptance speech before 84,000 in Denver. Republicans said Democrats made the switch because they feared the sight of empty seats.
Obama planned to hold an afternoon conference call with the tens of thousands of supporters bumped from the guest list when the speech was moved indoors, and campaign officials said they would try to arrange for those who had stadium tickets to attend another Obama event before Election Day.
Skies over downtown Charlotte were overcast Thursday morning, and the forecast gave a 40 percent chance of showers in the afternoon, leaving a potential opening for second-guessers.
In an election in which the economy is the top issue to voters, the president got some encouraging news from new reports that the number of people seeking unemployment benefits fell by 12,000 last week and that businesses stepped up hiring in August.
Among those giving warm-up speeches for the president Thursday night: Vice President Joe Biden and actress Eva Longoria.
Longoria, appearing on NBC's "Today," said she's "been in the trenches" for Obama defending his record and promised her speech will be very different from Clint Eastwood's meandering remarks to the Republicans a week earlier.
"No empty chairs," she promised, a reference to Eastwood's conversation with an empty chair representing Obama.
Sen. Dick Durbin, D-Ill., was speaking too, and he gave voice to the Democrats' nervousness about the GOP advantage in fundraising during a morning interview on CNN, citing the dollars pouring in from Republican-leaning super PACs.
"We've got 17 angry, old, white men who are pouring in millions of dollars, carpet bombing every candidate in sight," Durbin said.
First lady Michelle Obama aimed to help the Democrats catch up, appearing at a private meeting of Obama's national finance committee.
Even as the president asks voters to stick with him, Mitt Romney and the Republicans keep nudging Obama's supporters to rethink their allegiance to a president seeking re-election in a time of weak economic growth.
The party released a new ad Thursday called "The Breakup," in which a woman tells the president: "This just isn't working ... You're not the person I thought you were. ... I think we should just be friends."
On Obama's big day, Romney was in Vermont preparing for the fall debates. He planned to drive back to his home in New Hampshire in the afternoon.
Underscoring the importance of a turn of phrase, the president said in a TV interview that he had "regrets for my syntax" when he told a campaign crowd last month that people who had a business "didn't build that." Romney turned the president's line into a rallying cry, claiming Obama overstated the importance of government's role.
But Obama said he stands by his point that the government has provided strong support to small businesses. "Everyone who was there watching knows exactly what I was saying," he said in the interview with WWBT in Norfolk, Va.
Former President Bill Clinton set up Obama's speech with a rollicking turn on the stage Wednesday in which he offered a strong defense of the president's economic stewardship.
"He inherited a deeply damaged economy, put a floor under the crash, began the long hard road to recovery and laid the foundation for a more modern, more well-balanced economy that will produce millions of good new jobs," said Clinton the last president to see sustained growth, in the 1990s. "Conditions are improving and if you'll renew the president's contract, you will feel it."
Clinton also preached bipartisanship and a pullback from politics as "blood sport" this near the end of back-to-back conventions that feasted on rhetorical red meat and even as he ripped the Republican agenda as a throwback to the past, a "double-down on trickle-down" economics that assumes tax cuts for the wealthy will help everyone down the ladder.
Obama campaign strategist David Axelrod, also appearing on morning talk shows, said Clinton's speech had set out the economic choices, "so now the president can talk about the future having some of that underbrush out of the way."
Former Philadelphia Mayor Ed Rendell, a past Democratic Party chairman who appeared on "CBS This Morning," said that for all the excitement of the convention, he's still worried "about the base turning out to the degree they did" for Obama in 2008. He cited the battleground states of North Carolina and Virginia in particular.
Speaking of the convention speeches delivered by the first lady and the former president, Rendell added: "The beauty of Michelle Obama and Bill Clinton is they stoked the base."
Motivation was not an issue in the convention hall, at least not when Clinton spoke.
The hall rocked with cheers as Clinton strode onstage to Fleetwood Mac's "Don't Stop," his 1992 campaign theme song, and he held the crowd rapt as he drifted off his prepared remarks for about 50 minutes.
He accused Republicans of proposing "the same old policies that got us into trouble in the first place" and led to a near financial meltdown. Those, he said, include efforts to provide "tax cuts for higher-income Americans, more money for defense than the Pentagon wants and ... deep cuts on programs that help the middle class and poor children."