The former South Carolina Rep. Mark Sanford, who is challenging President Donald Trump for the Republican presidential nomination, has called Trump “unhinged” and “insecure.”

The former governor said he is appalled by the president’s penchant for lambasting his critics. Trump labeled the former Secretary of State Rex Tillerson: “dumb  as a rock.” The president branded the former Secretary of Defense Jim Mattis, “the world’s most overrated general.”

Sanford says that he wants to take the GOP on a more prudent fiscal path.

Trump has also recently made a dig at Sanford on Twitter where he mentioned the 2009 sex scandal that had threatened the former governor’s political career.

In spite of the mutual animosity, Sanford is convinced that the House Democrats led by Speaker Nancy Pelosi (D-California) should stop trying to impeach Trump as that would be counterproductive.