There are 235 D's in the House and only 80 or so on record of supporting impeachment, they don't have the votes.
I think a lot of the Dems who haven't come out on record supporting impeachment are taking advantage of the fact that there is no threat of vote.
I'd at least like to believe that if the House was forced to a straight yes/no vote it'd pass. And if that isn't the case, any rep voting no should be called into question.
Also, I believe that the top Dems like Pelosi repeatedly speaking out against impeachment lessens the likelihood of the smaller fish sticking their necks out to advocate for it.
Either way, salute to the 80 Dems with courage.