Not commenting on the validity of the poll, but assuming Democrats believe it, sitting on the impeachment allows time for support of impeachment, more pressure on republicans to allow witnesses, and pushes all this closer and closer to the election. If the Democrats believed support for impeachment was declining, then it would be in their interest to push through it quickly and get it over with.
If you dig down in the story, you’ll find only 42% of Americans want Trump removed from office.
Those numbers haven’t appreciably changed since December. The lines of difference remain solid.
A huge disappointment for the Democrat media.