Former Mississippi Gov. Ray Mabus on Saturday condemned Gov. Tate Reeves' decision to declare April as "Confederate Heritage Month" —- calling it "incredibly hurtful" and "dead solid wrong."

It celebrates "something that was truly awful: people trying to own other people," he added. 

"First, I didn't do it when I was governor," Mabus told CNN in a video clip posted on Instagram by anchor Victor Blackwell. "And second, Confederate heritage? Really? The heritage that I think of with the Confederacy is slavery, is treason and is losing. Which of those heritages are we really honoring here?"

Mabus, a Democrat who was Navy secretary under then-President Barack Obama, said the move was "part of the 'lost cause' narrative ... that came about a few years after the Civil War in an attempt to reassert white supremacy."

"What it does is incredibly hurtful. It is incredibly harmful and it honors something that we should learn about, know about, but definitely —- definitely — not honor," he said.

There "certainly should be some political pushback," Mabus added.

"I think that anyone that thinks that this is something that should be done, that this is something that will help in some way, is just dead solid wrong," he said.

On April 12, the day the Civil War erupted in 1861, Reeves signed a proclamation marking April as Confederate Heritage Month in the Magnolia State.

It was the fifth time he's done so, according to the Mississippi Free Press.

In his proclamation, Reeves, a Republican, said it was "important for all Americans to reflect upon our nation's past" and "gain insight from our mistakes and successes."

Reeves also urged "a full understanding that the lessons learned yesterday and today will carry us through tomorrow if we carefully and earnestly strive to understand and appreciate our heritage and our opportunities which lie before us."

A Reeves spokesperson told Mississippi TV state WAPT that five state governors, "Republicans and Democrats alike," have signed similar proclamations over the past 30 years.

Mississippi was the second state to join the Confederacy. The last Monday in April is a state holiday known as "Confederate Memorial Day."