There are two schools of thought on this, in my opinion, the political ramifications for not doing it and the constitutional duty for doing it.
As has already been discussed, impeaching could cause a backlash, especially since its unlikely the senate would vote for impeachment as well. We already know how trump and Republicans would spin it and we know how terrible the Democrats are at messaging, so it would be a political loser.
However, if the president meets the threshold for bringing impeachment then it is the house's constitutional duty to impeach trump. If a president is unfit for office then it doesn't matter what the political cost might be. Doing nothing is an invitation to do worse and sets an awful precedent.
I think the dems should impeach and lay out their case for the American people, if Republicans want to put their party before country then let them hang themselves.