but the impeachment talk makes the GOP look crazy crazier, and both turns off the undecided and motivates Democrats to maybe, you know, vote in the midterms.
There are several legitimate issues to impeach the Obama administration on (assassination of U.S. citizens, stacking the deck against the judiciary with state secrets, gathering intelligence on members of Congress and lying to them about it in a Senate hearing, etc.) The irony here is that this would threaten the profits of the industries that control the Republican party, so no Republican presidential hopeful would ever want to successfully impeach and set a precedent against their own ambitions.
Democrats, young voters, etc. are notoriously lazy midterm voters and nothing short of an unforeseen scandal of epic proportions right before election day would motivate them to displace incumbents. Republicans have this election in the bag and they know it.