WASHINGTON – President Barack Obama plunged on his first day in office into the task of governing a nation he vows to change, calling together U.S. economic and military leaders today to address America’s daunting challenges.A day after claiming his place in history as the first black U.S. president, he is faced with pulling the U.S. economy out of its nosedive even as he moves on his promise to withdraw American forces from Iraq while sending still more soldiers to America’s other war in Afghanistan.After returning to the White House from a round of inaugural balls at about 1 a.m., Obama ventured into the Oval Office for the first time as president around 8:30 a.m., presidential spokesman Robert Gibbs said.He and the new first lady then headed to the National Cathedral for a prayer service, a tradition dating to the country’s first president, George Washington.The Rev. Sharon Watkins, the first woman president of the Christian Church (Disciples of Christ), a Protestant group, was also the first woman to deliver a sermon at the National Prayer Service.In addition to meeting with his advisers, Obama was welcoming public visitors into the White House, as Congress was scrutinizing his economic revival plan and taking up the nominations of Hillary Rodham Clinton as secretary of state and Timothy Geithner for treasury secretary.A new poll underscored the sense of anticipation that accompanied Obama into office.The Associated Press-Knowledge Networks survey found that by a 3-1 margin, people feel more optimistic about the country’s future now that Obama has been inaugurated, including 30 percent of Republicans.A meeting with his economic team was planned to assess his approach and plot the way forward. Taking over the White House with 11 million Americans out of work and trillions of dollars in stock market savings lost, Obama said that turning around the limping economy is his first and greatest priority.Congress already has given him a second installment of financial-industry bailout money, worth $350 billion, and is fast-tracking a massive economic stimulus bill of $825 billion or more.”Fortunately we’ve seen Congress immediately start working on the economic recovery package, getting that passed and putting people back to work,” he said in an ABC News television interview. “That’s going to be the thing we’ll be most focused on.”The breakdown of confidence in the country’s banks, occurring on the same day as his inauguration, gave the matter fresh urgency. Financial stocks, many of them falling by double digit percentages, led a huge drop on Wall Street Tuesday that left the major indexes down more than 4 percent.The market’s faith in the outgoing Bush administration’s $700 billion bailout effort was already waning. Many experts believe Obama’s administration will have little choice but to pump more money into the banking sector or create an entity to buy banks’ soured assets such as subprime mortgages so they will start lending again.Addressing the war in Iraq that he has promised to end was featuring prominently in Obama’s first day as well.According to officials, Obama will conduct a video teleconference late in the afternoon with members of the National Security Council as well as the U.S. military commanders in the two war zones.Obama has said he wants U.S. combat troops out of Iraq in 16 months, as long as doing so would not endanger either the Americans left behind for training and terrorism-fighting or the security gains in Iraq. He has said he would use that drawdown to bolster the U.S. presence in Afghanistan, where a resurgent Taliban has been gaining ground.Summoned to the White House to discuss the way ahead in the wars were Defense Secretary Robert Gates – the lone Republican Cabinet holdover from the Bush administration – along with chairman of the Joint Chiefs of Staff, Adm. Mike Mullen; the top military commander in the Middle East, Gen. David Petraeus, and other members of the security council.Participating from the war front were to be Gen. Ray Odierno, the top U.S. commander in Iraq, and Gen. David McKiernan, the top commander in Afghanistan, according to two senior military officers.The officials spoke on condition of anonymity because the meeting has not been officially announced by the White House.While Obama gets to work in earnest at the White House, Congress planned to do its part.A Senate committee was taking a close look at Obama’s $825 billion economic revival package. On the other side of the Capitol, the House planned a vote on legislation setting conditions on Obama’s use of the new infusion of $350 billion in financial bailout money.Getting the Obama administration fully staffed also was proceeding.Within hours of Obama’s swearing in, the Senate approved six members of his Cabinet. His choice of Clinton to be secretary of state awaited a Senate vote Wednesday.Also left unconfirmed was Geithner, the nominee to head the Treasury Department. He faces the Senate Finance Committee, also Wednesday.Geithner issued an apology for his initial failure to pay payroll taxes he owed while working for the International Monetary Fund, saying the oversight was “careless” and “unintentional.””I should have been more careful,” the secretary-designate told the Senate Finance Committee. Its chairman, Max Baucus said he thought that Geithner had made “disappointing mistakes” but also said he needed to be confirmed so he could get to work on solving the country’s financial crisis.The new president signaled that a flurry of executive actions, studied and prepared during his two-month-plus transition, should be expected soon.Among the possibilities for the first day was the naming of a Middle East envoy, critical at a time of renewed hostilities between Israelis and the Palestinians; an order closing the U.S. military prison at Guantanamo Bay, in Cuba, a move that will take considerable time to execute.Beyond that, the new president could overturn the so-called Mexico City policy that forbids U.S. funding for family planning programs that offer abortion. Obama also was expected to lift President George W. Bush’s limit on federal funding of embryonic stem cell research.But Gibbs said that most such substantive executive orders will probably wait until Thursday or later. The push on Wednesday will be to issue orders making clear Obama’s intention to hold all White House staff to high ethics standards and to start delivering on the pledge of making his administration more transparent to Americans.

President Barack Obama, first lady Michelle Obama, Vice President Joe Biden, his wife Jill Biden, former President Bill Clinton, and Secretary of State nominee Hillary Rodham Clinton attend the inaugural prayer service at Washington National Cathedral. Photo by AP

Charles Dharapak