Obama didn't actually have multiple grand juries convened to look into him.  No, this isn't the work of the Democrats, no matter how much you may think it is.  The Republicans control both houses of Congress, they are the ones that called for a special prosecutor.  At this point, it is only a matter of time before Mueller either releases a report that is damning enough for the House to begin impeachment proceedings, or Trump gets tired of the job and quits.  I'd say that it is a close run thing, which happens first.