Some of the protests have been small events, promoted via Facebook groups that have popped up in recent days and whose organizers are sometimes difficult to identify. Others are backed by groups funded by prominent Republican donors, some with ties to Trump. The largest so far, a rally of thousands that jammed the streets of Lansing, Michigan, on Wednesday, looked much like one of the president's rallies — complete with MAGA hats or Trump flags — or one of the tea party rallies from a decade ago.