Wave, Wave, Wave!

I was watching cable news this morning as I am getting ready for work. I turned from channel to channel and all I heard from one network to the next was "the 2010 midterms will be a wave election for the Republicans." What evidence does the corporate media have to support this claim? Anecdotal polling data? Because Republican strategists say so? It sure is not actual early voting data for the 2010 midterms because when you review this data, it does not suggest a wave of any kind. So, tell me pundits, where is your data to substantiate that there will be a Republican wave in this election?