Indeed, a few radical Democrats wanted to impeach Trump on Day One, and technical justification for this existed based on emoluments clause violations. But this was a fringe opinion. The disturbing findings of the Mueller report pushed more in favor of impeachment, but still not enough, since it did not directly implicate the President. It was Ukrainegate and Trump’s own personal involvement therein that broke the camel’s back. It’s what changed Pelosi’s mind, and my own as well. Support for impeachment is now very mainstream.