Confrontations over immigration and border security are moving to the center of the struggle between the two parties, both in Washington, D.C., and beyond. And yet the most explosive immigration clash of all may still lie ahead. In just the past few days, Washington has seen the collapse of a bipartisan Senate deal to toughen border security amid opposition from former President Donald Trump and the House Republican leadership, as well as a failed vote by House Republicans to impeach Department of Homeland Security Secretary Alejandro Mayorkas for allegedly refusing to enforce the nation’s immigration laws. Simultaneously, Texas Republican Governor Greg Abbott, supported by more than a dozen other GOP governors, has renewed his attempts to seize greater control over immigration enforcement from the federal government. Cumulatively these clashes demonstrate how much the terms of debate over immigration have moved to the right during President Joe Biden’s time in office. But even amid that overall shift, Trump is publicly discussing immigration plans for a second presidential term that could quickly become much more politically divisive …