Just like they did when Nixon was trying to end the Vietnam War, and folks like Teddy the Swimmer and John Effin Kerry were holding their own negotiations with the North Vietnamese in Paris. Also, like the same two did working with the Sandanistas, against the Reagan administration, in the 80's.
In fact, the Democrats seem more interested in Foreign Policy when they are NOT in office. They certainly never seem to do anything useful about it when they are.
You make many good points. I remember some of the pandering by the Dems over the years to pathetic leaders that you mentioned. It was sickening but probably no worse that what a few Dems have done in this war.