Beats me. Maybe there would be bitter reaction, maybe there would be sporting support.
The GOP and RNC apparatus has clearly advocated for Specter.
They HAVE to support him... Think about it, if they don't, you'll see the DNC running ads saying that the RNC/GOP didn't support him, after x years of supporting their party. You also risk him switching the Dem side, or withholding votes on major issues...
If Toomey wins, you'll see the GOP/RNC support him 100%.