I don't think they have enough Democrats for it to pass the house, I doubt all of them would vote for it which is why they haven't tried it yet.
Trump impeachment effort once again rejected in House
The House voted to table Rep. Al Green’s article of impeachment 332 to 95, the third time his effort has gone down in defeat.
Looks like most Democrats are smart enough to know this is a stupid idea. Unless some smoking gun comes to light, it's not going to happen.