Republicans in the U.S. Congress are designing options that would raise revenue from high earners while preserving the 35 percent top income-tax rate, in a sign of preparations for a post-election session, said two Republican congressional aides.

The tax-raising options would be used only as part of a broad agreement on taxes and entitlement programs if President Barack Obama wins re-election. They are included in a toolbox to be opened after the Nov. 6 elections if Republicans make a political calculation to support a deal that raises taxes, said the aides, who requested anonymity to discuss the options.

The tax talk is part of discussions about post-election scenarios in Washington among congressional staff members while they wait to see who will control the U.S. House of Representatives, Senate and White House in 2013. Those talks are useful and also limited, because of the unpredictable emotional response that lawmakers will have to the election results, said J.D. Foster, a senior fellow at the Heritage Foundation, a Washington research group that favors small government.