According to four political operatives working closely with Republicans, leaders in both the House and Senate characterized some of the White House’s demands, which have yet to go public, as “poison pills,” saying they are impossible to achieve and that the White House staffers’ intent is to scuttle the deal for political gain.

The focus of their ire is on Stephen Miller, Trump’s senior policy adviser, who drafted the principles and has been behind several other controversial White House initiatives, including the ban on travel from several Muslim-majority nations. He is one of the few hard-right conservatives remaining in the White House after the departure of Trump’s former chief strategist Steve Bannon.

“We use to joke about President Bannon. Now it’s President Miller,” one senior lawmaker said in a meeting about the White House’s immigration and border security demands.