WASHINGTON » Four years ago, President Barack Obama and his staff spent the first day in the White House learning the basics. Not just the basics of governing, but also figuring out how to get cleared into their offices by the Secret Service, log on to their government computers and find keys to unlock office drawers.

They solved those problems long ago. Also in the rearview mirror are the economic recession, the Iraq war and the hunt for terror mastermind Osama bin Laden.

But plenty of fresh challenges lie ahead as the president and his team begin the first working day of the second term today.

Obama will quickly confront three fiscal deadlines that demand cooperation with the Congress, including raising the debt ceiling, which the House scheduled for a vote Wednesday. The deaths of three Americans in a siege on a natural gas plant in Algeria have renewed fears about the rise of terrorism in North Africa. And Obama must soon finalize the next phase of the drawdown of U.S. troops in Afghanistan.

Before getting down to business, Obama had a few more inaugural obligations to complete today, including a prayer service at the National Cathedral. It was the third straight day of religious worship for Obama surrounding his second inauguration, including Sunday and Monday at Metropolitan African Methodist Episcopal Church and St. John’s Episcopal Church, respectively.

The president also planned to celebrate today night with campaign and White House staff at a glitzy inaugural ball featuring singer Lady Gaga.

Otherwise, today is expected to be a normal working day at the White House. The president will meet with his top aides, and press secretary Jay Carney will brief the press.

Behind the scenes, the president and his advisers are working on the ambitious progressive agenda Obama outlined in his inaugural address, one that will require cooperation from a divided Congress in an era of looming budget cuts.

"We must make the hard choices to reduce the cost of health care and the size of our deficit," Obama said, speaking to the hundreds of thousands of people fanned out across the National Mall. "But we reject the belief that America must choose between caring for the generation that built this country and investing in the generation that will build its future."

Obama also plans to soon unveil proposals for a comprehensive overhaul of U.S. immigration laws, which is expected to be a central topic in Obama’s Feb. 12 State of the Union address. The president also will be seeking congressional support for the far-reaching package of gun-control proposals he unveiled last week, including an assault weapons ban and universal background checks for gun purchasers.

Obama also paid special attention to climate change during his inaugural address, an issue he spent little time on during his first term.

"Some may still deny the overwhelming judgment of science, but none can avoid the devastating impact of raging fires and crippling drought and more powerful storms," he said.

Still, it was unclear how much effort Obama would put into climate change legislation this year — or how much political capital he would have left to spend on the issue after tackling his other priorities.

The looming question over Obama’s entire second term is whether he can find a way to quell his confrontations with a divided Congress. Seeking to start off on a better foot, the president invited a bipartisan group of lawmakers to the White House ahead of his inaugural address Monday, including the Republican leaders with whom he has frequently been at odds: House Speaker John Boehner of Ohio, Senate Minority Leader Mitch McConnell of Kentucky and House Majority Leader Eric Cantor of Virginia.

Speaking to the throngs gathered on the National Mall, Obama implored Washington to find common ground when it can.

"We cannot mistake absolutism for principle, or substitute spectacle for politics or treat name-calling as reasoned debate," Obama said.

And seeking to build on the wave of public support that catapulted him to two terms in the White House, the president pressed for the public to get help him "set this country’s course." Tellingly, Obama sent an email shortly after his speech asking supporters to send their contact information to Organizing for Action. That’s the outside group formed by several top Obama campaign officials with the goal of supporting his legislative agenda.

Debates with Congress appeared to be far from Obama’s mind Monday. A relaxed president soaked in a full day’s worth of activities, starting with a morning church service and ending with two swanky balls.

Following his relatively brief, 18-minute inaugural address, Obama gazed over the crowd fanned out across the National Mall and said, "I’m not going to see this again."

He and first lady Michelle Obama climbed out of their armored limousine twice during the inaugural parade to walk a few blocks and wave to the jubilant crowd along Pennsylvania Avenue. And he danced and bobbed his head to the marching bands passing by his parade viewing box in front of the White House.

Even after his wife and family left the viewing box, Obama stayed to applaud each marching band and float that passed before him.

Associated Press writer Darlene Superville contributed to this report.