From my new Upshot column (co-authored with Kyle Dropp):

Despite the growing protests against President Trump’s executive action on refugees and other people from seven predominantly Muslim countries, relatively few members of his party have spoken out against the policy — a familiar pattern since the election. To date, no congressional Republicans have consistently resisted Mr. Trump or his agenda even though his approval ratings are already historically low for a new president.

Although some Republicans may fear a voter backlash in the midterm election, the greatest threat to re-election for most G.O.P. members of Congress is still a primary challenge. That’s what many legislators probably fear they will get if they oppose Mr. Trump, who is viewed overwhelmingly favorably among their partisan base, according to polling data.