WASHINGTON Barack Hussein Obama launched his second term as the nation’s 44th president Monday, urging an increasingly divided nation to move past polarizing debates and live up to its founding ideals by uniting to solve the country’s problems.

“America’s possibilities are limitless, for we possess all the qualities that this world without boundaries demands: youth and drive, diversity and openness, an endless capacity for risk and a gift for reinvention,” he said on a crisp, sun-filled afternoon. “My fellow Americans, we are made for this moment, and we will seize it, so long as we seize it together.”

His 18-minute inaugural address – delivered in front of hundreds of thousands of people and televised to millions across the globe – offered a clear agenda for his second term, marshaling the federal government to protect the rights of gays and lesbians, combat climate change, provide opportunities for illegal immigrants, and help the downtrodden and middle class get a better foothold in a changing and still fragile economy.

A sea of spectators packed the National Mall to watch Obama, 51, sworn into office a few minutes before noon on the west side of the U.S. Capitol, the first Democrat in seven decades to twice win a majority of the popular vote. First lady Michelle Obama and daughters, Sasha, 11, and Malia, 14, looked on, as did former Democratic Presidents Jimmy Carter and Bill Clinton. The two living Republican former presidents didn’t attend, the ailing George H.W. Bush and son George W. Bush.

“O-bam-a!” the crowd chanted. “O-bam-a!”

Noticeably grayer than when he first took office, Obama had officially started his second term 24 hours earlier, after a brief private ceremony at the White House. Monday’s proceedings followed the tradition of delaying the public inauguration a day when the official date prescribed by the Constitution falls on a Sunday.

The nation’s 57th inauguration consisted of five days of patriotic parades and fancy balls, solemn prayers and countless receptions for donors and supporters.

“At what place would you wanna be on Inauguration Day?” asked Camille Page of Corona, Calif. “This is a once-in-a-lifetime experience. . . . I will be proud to tell my grandchildren about it.”

Monday’s events were jubilant, though they didn’t have the same level of excitement as four years ago when a young senator promising hope and change became the nation’s first black president. There were no official estimates of the audience Monday. Inaugural organizers said they believed 1 million attended, though they did not explain their estimate. Regardless, it was far short of the 1.8 million who attended in 2009 while still an above-average audience for a second-term inauguration.

“Last time there was a little bit more excitement. It was brand-new,” Kerry Kelty of Pittsburgh said of Obama’s first inauguration. “I don’t think people are disappointed, but reality hit.”

The crowds led to a maze of street closures, clogged subways, heightened security and the National Mall filled with 1,500 portable toilets, five large-screen TVs and 6,000 members of the National Guard in town assisting with crowd control.

After a bitter election and constant clashes on Capitol Hill, Obama used his inaugural address to encourage those with differing views to work together to accomplish something, even if it’s not everything.