NEW YORK (AP) -- President Barack Obama and Republican challenger Mitt Romney are returning to the sometimes-nasty rhetoric of a close presidential campaign after a brief truce, renewing their focus on two battleground states and preparing for next week's final, perhaps pivotal, debate.Romney and Obama set aside their differences - mostly - to poke fun of themselves and each other Thursday night at the Alfred E. Smith Memorial Foundation Dinner. On Friday, it's back to campaigning in Florida and Virginia, two of just a handful of states that will decide the election, now less than three weeks away.Obama was planning a speech at George Mason University in Fairfax, Va., rallying college students in the northern part of the state. Romney was to fly to Daytona Beach, Fla., for a rally with running mate Paul Ryan.While they're both focused on the South, an NBC News/Wall Street Journal/Marist polls released Thursday showed Obama retaining his lead over Romney in Iowa and Wisconsin, two Midwestern battlegrounds. Obama's campaign circulated a memo highlighting the president's strength during the early voting period in Ohio, where Romney has largely staked his hopes of winning the White House.But both kept relatively light public schedules as they planned to spend the weekend preparing for the third and final presidential debate, set for Monday in Boca Raton, Fla. Obama was leaving for the Camp David presidential retreat to prepare, while Romney planned preparations in Delray Beach, Fla.\The next debate is on foreign policy