You better hope that the Democrats haven't really opened up on Trump because they are keeping their power dry. Once Trump is the nominee, I suspect that the Democrats will open fire and that Trump will be found to be a target-rich environment.
They’ve been out to get Trump since the beginning and nothing stuck. They are out of bullets. The notion that they are holding back until Trump gets in a position to win is ludicrous. If he is the nominee, it is too late. They would have taken him out a long time ago if they could.