With most of Washington locked in a debate over just how big a bite should be taken out of a (relatively small) portion of overall government spending, one group of senators is pushing forward to face larger budget challenge. President Barack Obama has kept a cautious distance from the recommendations issued last year by his own commission on fiscal responsibility — particularly when it comes to entitlements like Social Security. But this bipartisan group of six senators, led by Sen. Mark Warner, D- Va., and Saxby Chambliss, R- Ga., is keeping the commission's proposals alive and drafting them into legislation....