It's not that you're pessimistic about Republican prospects. It's that you're pessimistic about Republican prospects after you're the one who swore to everyone to the very end Santorum would win after all.
That's really just normal after being so disappointed about something. After John Kerry lost in 2004 following my getting all hopeful about a Democratic victory, I became very pessimistic about Democrats' chances in future elections. It's at least partially something of a defense mechanism - you can't let down if you have low expectations, and you certainly can be pleasantly surprised.
