Sen. Chuck Grassley addressed the Iowa Freedom Summit today about his opposition to overturning the Supreme Court’s 2010 Citizens United ruling, criticizing the four justices who dissented in the case for having “an upside-down understanding of the Constitution.”

The right-wing group Citizens United, which brought the Supreme Court challenge that ultimately allowed for unlimited, undisclosed corporate spending is the summit’s principal sponsor.

The Iowa Republican added that “liberal elements in the United States Senate” who support a constitutional amendment overturning the court’s decision will put the country on a “slippery slope” that “could lead us to the abolishment of the Bill of Rights as we’ve known it for 230 years.”