Stocks added to gains in early afternoon trading on Tuesday after President Obama threw his support behind efforts by a bipartisan group of senators to negotiate a new deficit-reduction plan aimed at averting a debt default.

The Dow Jones industrial average <.DJI> was up 187.32 points, or 1.51 percent, at 12,572.48. The Standard & Poor's 500 Index <.SPX> was up 17.94 points, or 1.37 percent, at 1,323.38. The Nasdaq Composite Index <.IXIC> was up 52.53 points, or 1.90 percent, at 2,817.64.

(Reporting by Caroline Valetkevitch; Editing by Kenneth Barry)