Party lines, schmarty lines.  

The key thing that keeps Sens. Bob Casey, D-Pa., and Patrick J. Toomey, R-Pa., going while here in D.C. is the burning desire to topple the other in their annual softball showdown.  

Team Scrantonicity has faced off against the Hit It Toomey squad each summer for the past three years with mixed results. Scrantonicity throttled its foes 20-10 last year, but Team Toomey has wracked up more “W”s than losses over time.  

“Sadly team Toomey leads the all-time series 2-1. But I’m quite confident the series will be all even after tonight’s festivities,” a Casey aide assured HOH in a trash-talking email.  

Those looking to get swept up in softball mania should make their way over to the National Mall (Seventh and Madison streets NW) around 6:45 p.m. to catch all the action.  

Look for Casey to be snagging flies in the outfield (our tipster says the boss typically patrols right field), while Toomey tends to plant himself at third.