WASHINGTON (AP) - President Barack Obama's treasury secretary said Sunday he cannot rule out higher taxes to help tame an exploding budget deficit, and his chief economic adviser would not dismiss raising them on middle-class Americans as part of a health care overhaul. As the White House sought to balance campaign rhetoric with governing, officials appeared willing to extend unemployment benefits. With former Federal Reserve Chairman Alan Greenspan saying he is "pretty sure we've already seen the bottom" of the recession, Obama aides sought to defend the economic stimulus and calm a jittery public. Treasury Secretary Timothy Geithner and National...