President Trump is escalating his criticism of Senate Judiciary Committee Chair Chuck Grassley (R-Iowa) for his unwillingness to overhaul the “blue slip,” a move that has further dismayed Senate Republicans.

President Donald Trump threatened legal action over a Senate tradition Democrats have used to block certain judicial nominees, escalating a long-running dispute with Senate Judiciary Committee Chairman Chuck Grassley (R-IA).

Senators approve of a nominee by returning their blue slip to the Judiciary Committee Chairman. If a senator does not return their blue slip or returns it with objections, the nominee does not advance. In blue states like New York, some of Trump's judicial nominees have stalled out because Democratic senators have not returned blue slips.