WASHINGTON — A relaxed and upbeat Barack Obama invoked the spirit of Martin Luther King Jr. and lavished praise on two prominent Republicans in calling for a new spirit of bipartisanship. After visiting wounded veterans and helping volunteers paint a dorm for homeless teens in Washington, Obama dashed to three black-tie dinners Monday night. One honored Sen. John McCain, the Republican he defeated in November, and another honored Colin Powell, who was secretary of state for President George W. Bush. The third dinner was for Joe Biden, who will take the vice presidential oath of office before Obama becomes president on the Capitol steps Tuesday. Obama called McCain and Powell American heroes who set standards of patriotism and bipartisanship for all to follow. He hugged McCain onstage and called for Americans’ help ‘in making this bipartisan dinner not just an inaugural tradition, but a new way of doing the people’s business in this city.’ Throughout the day, Obama showed no hints of nervousness about becoming president within hours. ‘I don’t sweat,’ he told volunteers at Sasha Bruce House, a shelter for homeless teens in one of Washington’s poorer neighborhoods. ‘You ever see me sweat?’ […]