They knew damn well that what he did was impeachable.
The support didn't exist when they opened the investigation but as it went on, support grew as overwhelming as the evidence.
And all that was over a break-in at the Watergate Hotel, a mere drop in the bucket compared to the breadth and depth of the current administration's crimes.
Pelosi must IMPEACH OR RESIGN!
Right, what you are saying is that they started an investigation and support built right?
How would this be any difference? Nadler said as much that a investigation was being started.
As soon as the evidence is overwhelming, there will not be a choice and it will be exactly what you're saying you want.
If there is not evidence, because Trump was pulling a con of making it look like he was dirty but wasn't so he could use it later would also then come out.