I think Trump is trying to lure them into doing it.
I do too.
"Skin that smoke wagon and see what happens."
He is and it is their last round of ammo which is useless. He will hit them back with the mother load of info he has on them and use the Insurrection Act to boot both illegals and the deep state scum .
It makes sense he would bait them. Not a single voter who supports impeachment right now is going to vote for Trump under any circumstance. But constant investigations and attempting impeachment will encourage some less kooky, swing state democrats to stay home or even vote for Trump. If the economy continues to boom while the Dems do nothing but attack and stall, Trump wins easily.
Pelosi knows this, and has desperately been trying to reign in the AOC wing of the party. Tomorrow, we will see if she will continue, or give up and let AOC and Omar run the party. If she loses this fight, she will not seek reelection in 2020.