
Trump has dipped to 38.8% in FiveThirtyEight's polling average, a full percentage point below his previous low. According to FiveThirtyEight's adjusted polling numbers (which account for which way each pollster generally leans), he hasn't scored above 40% (adjusted) in over a week.
Meanwhile, he's dipped under 40% for the first time in RealClearPolitics's polling average, to 39.6%.
I think it's generally understood that once he gets into the low 30s, politicians will be even less willing to work with him. Seems like it'll just be a matter of time. So keep calling your representatives!