The two squared off for more than 40 minutes Sunday on NBC's "Meet the Press," in a state where polls show Casey, the state treasurer, with a lead over the conservative Santorum.
Santorum defended President George W. Bush and his administration, as well as the handling of the war in Iraq.
Casey in turn taunted Santorum for being a "rubber stamp" for Bush.
On the issue of balancing the federal budget, moderator Tim Russert asked Casey how he would do it. Casey said he would seek to repeal recent tax cuts for wealthy people making more than $200,000 a year, and retain a tax on very large estates, which Santorum opposes. But he would not identify specific federal programs he would be willing to cut, the Washington Post reported.
That led Santorum to interject: "What you heard from Mr. Casey is what you hear all the time -- no specifics, no answer," Santorum said.