Here's why impeaching Trump now is a good idea politically for the Dems:
Trump's base is strong and will be energized for 2020 regardless of whether or not the Dems impeach him, Republican turnout will be huge in 2020 either way
The way Dems win in 2020 is by turning out voters who stayed home in 2016, and to do that you need party activists to organize / canvas / phone bank
Democratic activists are on the extreme ideological end of the party and are very pro-impeachment, so impeachment will energize them to work their asses off
If you're not already part of MAGA nation, charges of corruption will more likely hurt your opinion of Trump than turn you off to the Dems
In summary, Dems likely will only help themselves with their base by impeaching Trump if all of this Ukraine business being reported ends up being true, and this is how they win. I don't buy the narrative that impeachment will energize the red hats like it did the Dems in the 1998 midterms because Trump's base is inelastic, they're ride or die for him and their support doesn't wax or wane like Democratic turnout does. Thus, impeachment is a (nearly) no-lose situation for anti-Trumpers in 2020.
Just my two cents, take it or leave it. What do I know after all, I'm just a government teacher. - LUCAS
I'm with you on all but one thing:
There are a lot of unenthusiastic Trump voters who don't particularly care for him but believe in bedrock Republican ideals the Democrats will never speak to. Making them stay home is key to beating Trump. An impeachment push is a red line voters like that who will believe that this isn't just a punishment for one man but rather the new normal of what happens when someone Pro Life/Pro Gun/Religious becomes president.
Basically it's an excuse for Never Trumpers and Family Values Moms who are grossed out by Trump to come home because he represents more than just himself.