They haven't won the White House or cemented a filibuster-proof, 60-vote Senate majority, but confident Democrats are already looking past November 4 to Election Day 2010. Their goal is to avoid mistakes while pushing a bold, voter-savvy plan that could break history's pattern and help them build on their majority. The gee-whiz idea: balancing the federal budget. "Nobody would think we could do it. That's why it's so bold and a winner for us," says a key Democratic Senate aide. And, he says, it's better than the alternative: If the Dems do get 60 senators and squander their advantage, they fear voters will sack them in 2010.