Sen. Pat Toomey, R-Pa., is warning President Trump that he and other Republicans won’t be bullied into abandoning NAFTA, and said Trump has no power to unilaterally withdraw from the agreement.

“To pressure us into voting for an agreement that diminishes free trade, some in the administration suggest offering a grim choice: either approve a diminished NAFTA, or the president will unilaterally withdraw the U.S. from the existing NAFTA, leaving no NAFTA at all,” Toomey wrote in an op-ed for the Wall Street Journal.