There are lots of obvious reasons why Trump should be impeached *now* – with only a week left in his term. But what are the less obvious ones?

* Knock Trump off balance – if he's fighting impeachment he isn't doing other things

* Force Trump to seek help from establishment conservatives – who will exact their own price

* Give the Democrats a lever to either move Pence on 25th Amendment or Trump to resign

* Long term – permanently stain Trump's presidency