Texas Rangers and county Sheriffs are the ultimate authorities in their jurisdiction. SS could claim federal authority, but would most likely have to back it up with a federal judge minimum. In the mean time, it just depends on who and how fast they want to press it.

In theory, the SS could be held with enough manpower for obstruction if they resisted. Would probably be allowed to continue as escorts. Odd thing, I dont recall in history where this has happened, so no preceedent. Regardless it wouldnt turn out well for anyone.