Sen. Chuck Grassley (R-Iowa) speaks at an immigration reform news conference on Capitol Hill in Washington, Feb. 12, 2018. With the fate of hundreds of thousands of young, undocumented immigrants in the balance, the Senate on Monday began an open-ended debate on immigration — an exceedingly rare step that, in effect, will allow senators to attempt to build a bill from scratch on the Senate floor. From left: Republican Sens. Tom Cotton (Ark.), Joni Ernst (Iowa), David Perdue (Ga.), and Thom Tillis (N.C.) (Er