WEST PALM BEACH, Fla. – It's either candidate's race to win as President Barack Obama and Mitt Romney prepare for their second debate Tuesday night, with just three weeks to go until the election and voting well under way in many states.

The Republican challenger had trailed the Democratic incumbent in national polls for weeks, but now has drawn even, benefiting from a boost of enthusiasm following a strong first debate performance 10 days ago. While Romney's standing has improved in some states, Obama retains an edge in the hunt for the 270 electoral votes needed to take the White House. The president also has far more ways than Romney to reach that magic number.

But that's not enough to calm nervous Democrats, even as they revel in Vice President Joe Biden's pull-no-punches turn on the debate stage Thursday night against GOP vice presidential nominee Paul Ryan. They are looking for an equally aggressive Obama to show up for the prime-time town-hall style debate in Hempstead, N.Y.