(CNN) -- Virginia Gov. Bob McDonnell apologized Wednesday for leaving out any reference to slavery in his recent proclamation designating April as Confederate History Month, calling it a "major omission."
"The failure to include any reference to slavery was a mistake, and for that I apologize to any fellow Virginian who has been offended or disappointed," McDonnell said in a written statement.
"The abomination of slavery divided our nation, deprived people of their God-given inalienable rights, and led to the Civil War," the statement said. "Slavery was an evil, vicious and inhumane practice which degraded human beings to property, and it has left a stain on the soul of this state and nation."
McDonnell also announced Wednesday that he would add language about slavery to the proclamation.
"(I)t is important for all Virginians to understand that the institution of slavery led to this (Civil) war and was an evil and inhumane practice that deprived people of their God-given inalienable rights," the new language says, "and all Virginians are thankful for its permanent eradication from our borders."
McDonnell's statement noted that while Virginia was home to the Capital of the Confederacy, it was also the first state to elect an African-American governor, L. Douglas Wilder, who McDonnell called "my friend."
In an interview with CNN on Wednesday, Wilder said that McDonnell's apology and his introduction of additional proclamation language was "the right thing for him to have done."
"Most people recognize that slavery was the cause of the (Civil) war," Wilder said, noting that McDonnell had called him Wednesday. "The war was not a glorious thing in our past. It was something that we were able to withstand in terms of tearing the country apart. ... Thank God that war ended with the Confederacy losing."
Not all Democrats were willing to forgive McDonnell on Wednesday.
"He has a right to apologize," Virginia State Sen. Henry Marsh III, a black Democrat, told CNN. "But I don't accept that as a good answer because this is a pattern of this governor."
"He says the wrong thing, he sends a signal to his base and then he makes an apology," Marsh said, "It's a question of whether or not he's sincere or not."
Other Democrats accepted McDonnell's apology.
"My great, great grandparents, their offspring and others were split up in the Commonwealth of Virginia & sold into slavery," Democratic strategist and CNN political contributor Donna Brazile said on Twitter. "Apology accepted
McDonnell is the first Virginia governor in eight years to issue a proclamation declaring April as Confederate History Month in the state, a move that drew criticism from Democrats and a civil rights group.
Former Virginia Gov. Tim Kaine, now Democratic National Committee chairman, issued a statement Wednesday blasting McDonnell's exclusion of slavery from the original proclamation.
"Governor McDonnell's decision to designate April as Confederate History Month without condemning, or even acknowledging, the pernicious stain of slavery or its role in the war disregards history, is insensitive to the extraordinary efforts of Americans to eliminate slavery and bind the nation's wounds, and offends millions of Americans of all races and in all parts of our nation," Kaine wrote.
"A failure to acknowledge the central role of slavery in the Confederacy and deeming insignificant the reprehensible tran sgression of moral standards of liberty and equality that slavery represented is simply not acceptable in the America of the 21st century," he continued.
McDonnell quietly declared April Confederate History Month after two previous Democratic administrations refused to do so.
"It is important for all Virginians to reflect upon our Commonwealth's shared history, to understand the sacrifices of the Confederate leaders, soldiers and citizens during the period of the Civil War, and to recognize how our history has led to our present," the proclamation reads in part.
Virginia Delegate Kenneth Alexander, chairman of the Virginia Legislative Black Caucus, said the governor's proclamation was offensive.
It "offered a disturbing revision of the Civil War and the brutal era that followed," Alexander, a Democrat, said in a written statement. "Virginia has worked hard to move beyond the very things for which Gov. McDonnell seems nostalgic."
The Virginia chapter of the NAACP also condemned the proclamation, The Washington Post reported. The group did not immediately return phone calls to CNN.
The Sons of Confederate Veterans asked the governor to declare April Confederate History Month in Virginia, which had seceded from the Union on April 17, 1861.
Brandon Dorsey, a spokesman for the group, told CNN Radio that Confederate History Month isn't about slavery or race, but about studying the four-year history of the Confederacy. He said it will also help draw visitors to the many Civil War battle sites in Virginia, helping to boost tourism.
"The proclamation's main goal is to call attention to the fact that there is Confederate history in the state of Virginia, of course, across the South," Dorsey said. "It's simply a tool to expose individuals to that history. ... It's not meant to discriminate against anybody."
Other Southern states have issued similar proclamations for April. In Alabama, Republican Gov. Bob Riley declared April, the month the Civil War began, as Confederate History and Heritage Month. His statement condemned slavery.
CNN Radio's Shelby Lin Erdman contributed to this report.