This worries me - if Sanders has the gumption to speak truthfully on this he may be a lot more dangerous than I thought.
It's just common sense though - why would any European country accept an undesirable immigrant that costs them thousands per month in welfare, health care, education, law enforcement and wage erosion when they can just give them a one-way ticket to the U.S. city of their choice?
Of course there are democrats who don't want to give the country away entirely, they just want enough new voters to cement their own hold on the reins of power.