The bipartisan effort to pass immigration legislation has driven a wedge through the heart of the Tea Party — with some of the GOP’s staunchest advocates and fiercest opponents of reform hailing from the insurgent movement. On one side, Sen. Marco Rubio (R-Fla.): A Tea Party hero who was one of the movement's early success stories, Rubio is leading efforts to sell the bill to the GOP's conservative wing. Sen. Jeff Flake (R-Ariz.) and Reps. Paul Ryan (R-Wis.) and Raul Labrador (R-Idaho), three other Tea Party favorites, have also been closely involved in the bipartisan negotiations.

 But others closely aligned...