The Democrats driving impeachment matters think they have nothing to lose. Removing Trump isn’t necessary: if impeachment does him any damage at all in next year’s election, that may be enough to defeat him in a close race. Even better, vulnerable Republican senators in places like Colorado and Maine might be toppled by their impeachment votes — no matter how they come down on the ultimate question. A vote not to convict and remove might hurt them with independents; a vote for conviction and removal would cripple their chances of turning out their own party’s maximum number of supporters. Either way, impeachment brings Democrats closer to control of the Senate.
Impeachment has a further partisan benefit for Democrats: it distracts from the weakness of their presidential candidates. It’s obvious that the Democrats aren’t speaking to the middle ground of American politics. What is an average voter to make of a party whose big ideas, as represented by the presidential field, are prolonged deployment in Syria, a Medicare for All plan that depends on fantasy accounting, door-to-door gun confiscations, and tax penalties for churches that don’t accept the sacraments of gay marriage and transgenderism? And Joe Biden is not as far out on a few of these questions as his rivals are, he’s up to his hair plugs in other embarrassments, from his vote for the Iraq War to his association with the Obama administration’s immigration policies — too weak for the right, too harsh for the left. You can see why electability-minded Democrats are eager for the 2020 election to be defined by something other than the issues.