Former Secretary of State Colin Powell said Sunday that President Donald Trump has “drifted away” from the Constitution.

Powell, a Republican who served in George W. Bush’s administration, endorsed presumptive Democratic nominee Joe Biden in the interview.

“We have a Constitution. And we have to follow that Constitution. And the President has drifted away from it,” Powell said to CNN’s Jake Tapper on State of the Union.

The statement comes after Trump threatened to invoke the Insurrection Act, which allows the President to use military force within the US. Trump cited a need to stop looting and rioting, though some suggest the move would also prevent peaceful protests in response to the recent death of George Floyd.

In addition to Powell, a number of military leaders spoke out against the President and his response to police brutality protests. Generals Jim Mattis, John Kelly and John Allen all expressed concern about the use of the military and rule of law.

Trump spoke out against Powell on twitter on Sunday, calling the four-star general, “highly overrated” and attacking the former Secretary of State’s involvement in the 2003 invasion of Iraq.