Unfortunately Mad Maxine is correct. There is no legal definition as to what "high Crimes and Misdemeanors" actually constitutes. Now, stating that the president has committed high crimes and misdemeanors because he's just a poopy head, now that backlash against those insane D's will send my schadenboner past the Triangulum galaxy.
There could be such a definition, in infinitesimal detail, and Trump-Haters would ignore it. That there would be ballot-box consequences for that kind of tyrannous action would probably deter a good number of Ds, so even with a 5 or 10 (or 20?) seat majority I don't think many Ds would vote to impeach Trump on frivolous grounds.