Between the lines: People who’ve heard Mulvaney make this remark say he wasn’t joking or even exaggerating. He appears to genuinely believe that impeachment will have a profoundly positive effect on Trump’s political fortunes, according to 3 sources who have heard Mulvaney make the 45-state prediction.
Mulvaney also believes that the longer the impeachment process drags on, the better it is, politically, for Trump, these sources added.
Mulvaney did not stipulate which 5 states he thought Trump would still lose when he made these comments, a source who heard them said.
His view appears to be based more on instinct than polling data. I have seen no polling that supports his prediction, and at this early stage, responsible polling analysts are extremely wary of predicting which party will benefit more from impeachment in 2020.